I’ve made no mention of the lubavitcher rebbe himself.
I’m not a chabad chossid. As such, It does not really concern me if he was in fact a tzadik upon whom avodah zara was foisted, or if he was a maisis umadiach. What matters is that currently, there is a growing, evolving avodah zara ideology in chabad. The evidence to this is quite undeniable(I can supply you with much more, if you’re interested). That ideology was growing while the lubavitcher rebbe was alive(the brisker rov and chazon ish were noteably very wary at the time), but exploded exponentially after he passed away.
Either way, to your point: Gedolei yisroel not only corresponded with the likes of elisha ben avuya, but even learned from him directly! And lest you think that we are not on the level to do that nowadays, Rav Yaakov Emden also had a lengthy back and forth with Moses Mendelssohn sr”y, ending with a letter condemning him for straying from yiddishkeit to the point where he owned a dog (yes, dog ownership was indicative of deep defection from Torah, according to Rav Yaakov)
You left out Rav Hutner from your list of rabbonim – it’s noteable, because if you speak to a chaim berliner, or anyone who was close to him .. the question of Rav Hutner’s correspondence with the lubavitcher rebbe and the former’s opinions on the latter are quite evidence that correspondence has nothing to do with what a gadol holds of someone.
Also among the rabbonim you omitted was Rav Pam. Rav Pam originally said that we should stay out of the machlokes and that Rav Shach was talking only to bnei eretz yisroel. In his later years, when the personality cult became more apparent, Rav Pam retracted.
Again, I have no personal opinion of the lubavitcher rebbe, nor am I interested in forming one. He could have been a baal nissim and tzadik yesod olam, but that has nothing to do with my concerns.
It will not permit me to eat the meat and drink the wine of suspected idol worshippers, no matter how holy their rebbe may have been.