Da, most of the tanya is based on kisvei arizal, firstly.
Secondly, the same can be said of learning rav chaim with a bochur, who expresses doubt after someone asks him some good kashya
Some chasidishe people aren’t used to vigorous kashas. learn xhasidus with someone qualified, not just anyone with a long jacket. a serious lomed Torah doesn’t doubt their mesorah because of kashos.