Shkoiach for being moser din al chaveiro. With friends like that . . . .
Every single mainstream gadol who has discussed YCT has said that they are beyond the pale. They are de’ios kozvos. Leitzanusa d’avoda zara is muttar. Perversions of the Torah as the gedolim have said, surely qualify.
Check out Chazon Ish Emunah ubitachon 3rd Perek where he talks about Midos Tovos, Lashon Hara, yored imo l’chayav, are all dependant upon Halacha.