This surprising statement requires threefold fine-tuning:

– On the first point: Please remember that the General Chapter is the supreme instance of the Fraternity; it designates the Superior General and his two Assistants for 12 years (§ V, 1 of the Statutes).
This same Chapter is also entrusted with the essential mission of «verifying whether the Fraternity applies […] its Statutes and strives to preserve their spirit" (§ V, 2).
During his mandate, the elected Superior General enjoys the broadest powers to govern and administer the Fraternity with the help of his Assistants. Together they form the General Council.
In addition to these rules, and following the General Chapter of 2006 who adopted the principled position: «no practical agreement with Rome without doctrinal agreement», the July Chapter 2012 has established specific provisions that specify the conditions for a possible "canonical normalization" of the Fraternity: in this hypothesis, a preventive extraordinary "deliberative" chapter must be held, that is, equipped with the power to decide on the guidelines taken into consideration.
Not having been repealed, these provisions are always in force: every action in this domain therefore requires the convocation of the Chapter, of his complete information and therefore of his deliberation on the content of the project in question, after verification of the six conditions formulated in 2012.
The decision voted by the Chapter is imposed on the General Council and on all members of the Fraternity.
This is what Monsignor declared. from Galarreta to Villepreux he 13 October 2012:

It follows that the Superior General is not the "only" competent person to lead the process of normalization with Rome. On the contrary, he has an authority above him that, legally, it is the "sole" competent to sovereignly define the position of the Fraternity. Consequentially, Don Thouvenot is very wrong on this point.
And seeing that he, by virtue of its functions, he is considered as the spokesperson of the General House, we are surprised that Mons. Fellay did not react.
II – On the second point, it is evident that the so-called world "of Tradition" far surpasses, for its various ramifications, societies and religious communities, the perimeter of the Society of Saint Pius. It is enough to remember the refusal of Mons. Lefebvre every time someone wanted to make him the "chief of the traditionalists"!
The formulation that would attribute to the Superior General «responsibility for relations between Tradition and the Holy See» is clearly a perhaps involuntary inaccuracy, and Mons. Fellay should also correct his Secretary General's statements here.
III – On the third point, Don Thouvenot wrongly refers to the Founder to validate the current position of Mons. Fellay as the one in charge of leading the discussions with Rome. He forgets that since after the 1988 an essential parameter has been changed, namely that the Superior General, regarding any canonical normalization of the Fraternity, was submitted in 2012 to a prior agreement with the Chapter.
Mons. Lefebvre had not found himself in a similar position during his talks with Rome, and the parallel made by Don Thouvenot between the situations of 1988 and 2018… it's an anachronism.
And here too, Mons. Fellay should correct his collaborator's statements.
But it is unlikely that he will do so.… Because?
Why Mgr. Fellay himself in recent years has deliberately failed to convene and consult the Chapter before accepting the jurisdiction granted by Pope Francis regarding some sacraments: penance and extreme unction at the end of 2015, order in the summer of 2016 and marriage in 2017; while prior authorization was required, since in all these cases it is a "normalization" – certainly partial, but indisputable – of the situation of the Fraternity.
So, without risking making a reckless judgment, one can think that he has the intention of practicing the same procedure for the final normalization of the Fraternity, which would result from its erection as a personal Prelature.
In this sense, the opinion expressed by Don Thouvenot from Germany and the determination with which he declares that the authority of the Chapter would instead be transferred to the Superior General, It's a worrying sign.
Assuming that the question of the Prelature is actually "posed" during the Chapter scheduled for next July, these declarations of the General Secretary imply that the function of the supreme instance of the Fraternity, if the matter will actually be addressed, would be reduced to a simple "consultation", or rather to a "framework resolution" which would give the Superior General the power to deal with the dossier; with the Chapter which would thus be set aside and reduced to a mere "ratification office".
In this way, the underlying doctrinal debate would be discarded.
Under these conditions, how to guarantee that the Chapter can carry out its task which is to verify the conformity of the normalization project with the Statutes, on the one hand, and to the "spirit" that inspired them by will of the Founder, on the other?
If ultimately this scenario is pessimistic (the realist?) turned out to be correct, and the Chapter, the one in July or another, came to authorize the transformation of the Fraternity into a personal Prelature, the «Copernican revolution» – as J. called it. Madiran – of the work of Mons. Lefebvre would be brought to fruition and the legacy of the great prelate would fall like a ripe fruit into the hands of the cultists of the Second Vatican Council.
In the new canonical context in which it would find itself, under the power of Pope Francis, what kind of protection could the Fraternity hope for from conciliar Rome?
If in fact the Superior General (or the Chapter) they "forget" or circumvent the directives given by the Monsignor. Lefebvre after the consecrations, the statutory constraints of the Fraternity and the "limits" – already softened – decided in the Chapter of 2012, how could the Society demand that the Roman modernists honor their commitments when the Society itself will be totally under their legal protection?
Imagine that current Rome will respect the doctrinal and pastoral space of the Prelature, it means knowing this Rome badly; also taking into account the fact that Mons. Fellay takes his liberties with the internal rules of the Fraternity and ignores the prudent warnings of the Founder.
Who will be able to ensure that at that point the Fraternity, one day or another, does not suffer the fate of the Franciscans of the Immaculate Conception?
Before the decisive step towards the Prelature is taken and the irreparable is reached, the last hopes are placed in the capitulars themselves: that they do not renounce their responsibilities on every aspect of the issue.
In these difficult circumstances, it is hoped that their conscience will be firmly oriented along the paths of supernatural prudence, even if they risk a confrontation with those who seek impossible compromises to the detriment of the battle for the Faith.
For this we pray to Saint Joseph, Patron of the Universal Church.