See the interesting comments between Miguel and Anon on this subject under this article at The Remnant, alleging (correctly) that BXVI was merely playing the long game, and SP was designed to crush tradition:
https://remnantnewspaper.com/web/index.php/articles/item/6322-archbishop-gaenswein-traditionis-custodes-broke-pope-benedict-s-heart
Those comments are good.
The short video that was included in the link was good. Here's an excerpt:
Interviewer:
"As Pope emeritus, he was around to see the promulgation of Pope Francis motu proprio Traditionis Custodes. Was he disappointed?"
Ganswein:
"It hit him pretty hard. I believe it broke Pope Benedict's heart to read the new motu proprio, because his intention had been to help those who simply found a home in the old Mass to find inner peace, to find liturgical peace, in order to draw them away from Lefebvre."
Ganswein's response above is very telling, as the comments you mentioned refer to. It Ganswein is correct, in that B16 wanted to draw Catholics away from Lefebvre, it could be that he was only trying to draw those who wanted the old mass, and who were not too concerned or fussy about the doctrinal problems that accompany the new mass and conciliar church. It makes a certain amount of sense.