the Sefer Hachinuch is not a majority opinion among Rishonim
Many of the MO positions are very far from being majority opinions. Are you equally vocal in opposition to those? If you want to follow another legitimate opinion, that is your prerogative. And when we follow the Sefer HaChinuch on Tochacha, that is our prerogative.
the Amora Rava said (don’t have the source in front of me at the moment) that it is less of a transgression to be with a sofek eshes ish than to embarrass someone in public. The Rif, Rabeinu Yonah, several of the baalei Tosfos clearly disagree with the Chinuch, and even the Rambam, while he doesn’t include it as yehareg v’al yaavor, sees embarrassing someone in public as shfichas domim.
That is all completely irrelevant to the discussion of giving tochacha. The Halacha is also that it is strictly forbidden — according to ALL shittos — to kill someone. Yet, under certain circumstances, we can kill someone who violated Shabbos or committed blasphemy or a number of other reasons. Similarly, when we are mandated to embarrass someone with tochacha (i.e. as the SHC describes), it has no relation to the prohibition of embarrassing someone, much as Beis Din killing someone has no relation to the prohibition of Thou Shall Not Kill.
and it is even broadly in the context of rebbe talmid or talmid rebbe
The Halchic obligation to give tochacha, when appropriate, applies to every Jew regarding every other Jew. It is not limited to or between a rebbe/talmid relationship.
If you ask “What is MO and is it the preferable mode of Judaism?”, you are missing the point. Are the tenets of MO appropriate for you, or your family, or within your Rov’s direction to you? THAT is the question that is appropriate. If it isn’t preferable for you, fine, I won’t argue. But if you are arrogating the right to interpret Torah for others in defiance of their own halachic guidance, you are again falling into the trap of haughtiness.
You completely missed the point. Reread my first post. I specifically wrote: “If Modern Orthodoxy would be a Kiruv stage for people who aren’t yet ready for real Torah life, that would be fine.”