Ortho, i have no opinion about the Lubavitcher rebbe as a person, of he was a tzadik or not. It isn’t my business; i only concern myself with halachic and hashkafic problems that he and/or his followers promulgated. If after 120 i see the Lubavitcher rebbe way up there in shomayim, i won’t be happy or unhappy; I’ll just acknowledge that he was a tzadik. If he isn’t there at all, i likewise wouldn’t have a reaction – i don’t give much thought to him as a person. It only comes up when Lubavitchers think that he was uncontroversial, and this simply isn’t so. It shouldn’t rock ones world to know that some were against your rebbe – my rebbe, rav belsky, had a lot of detractors, some of whom i respect very much. But it doesn’t matter to me, because i accepted him as my rebbe based on the Torah expertise he showed me and being around him ,seeing his middos and hanhagos.
But in chabad, people are extremely offended at the thought of someone not holding of the person they call the “nasi hador,” even though only in their own circles was he considered a leader – a leader of s generation, for instance, rav Moshe, the chazon ish, rav chaim kanievsky…has to be accepted by virtually all of klal yisroel, and the Lubavitcher rebbe simply wasn’t. Large parts of the klal were against him, and many groups simply didn’t care about what he had to say. And that’s a truth that chabad needs to be aware of.