if you honestly claim that he doesn’t denigrate misnagdim as a whole
So you have a problem that the Frierdiker Rebbe denigrated anonymous Misnagdim. And I don’t think Frierdiker Rebbe meant to denigrate all Misnagdim, and he definitely did not denigrate the Gedolei Hamisnagdim.
Yet, in this thread, you had someone explicitly calling the Mitteler Rebbe a liar[1]. Without any source (just a conjecture, which itself has no source or foundation – he never actually said that he talked to a Chassidisher Rov who told him that Chassidisher Derech HaPsak ignores the Alter Rebbe completely. And even if it’s true, he’ll trust a modern Chossidisher Rov over a second hand source over what happened over two hundred years ago, just because he’s not Lubavitch). And no one called him out on this! Lo YeUman Ki Yesupar.
[1]. And you can’t say “well, it was a work of fiction”. You don’t write “fiction” in a Hakdama to the Shulchan Aruch. It’s either truth, or a lie. And rather than think a bit trying to farentfer the sons of the Alter Rebbe, he just called them liars. Can you imagine the righteous indignation if one of us said that about Reb Chaim Volozhener?