it’s not merely that Chabad accepted some type of kulah, but rather, it became a bad thing to sleep in the sukkah, which is backwards.
No, it’s not a bad thing, as the Rebbe wrote to those who had a minhag to sleep in Sukkah to keep their minhag.
Is it backwards that people davka don’t eat in the Sukkah on Shemini Atzeres? Or that people davka light menorah indoors? Both of which are seemingly against halacha?