“Rav Menashe Klein zt”l (chassidish posek who clearly understands chassidus and still says yechi is apikorsus)”
I read his Tshuva. IIRC he never says that Yechi is Apikursus.
And if you read the entire Tshuva, you will see the great Kovod he accords the Rebbe, and how he’s distraught over what some are doing to besmirch the Rebbes memory. Rav Klein was very close with the Rebbe, and with Lubavitch. In fact he was one of the Bochnim of the Machon LeHoraa of the Lubavitcher Yeshiva in Morristown NJ until his passing several years ago.
As for the other names you mentioned, surely you know that for obvious reasons no Lubavitcher will pay too much attention to what they think about us.