TS, my proof is both from the reluctance of the mainstream to distance itself absolutely, communally from the meshichisten, as well as from my experience talking with antis who never are able to bring themselves to say “no” when asked if they think the lubavitcher rebbe was the messiah. They will say “anyone CAN be” “what difference does it make if he is…if he is, will you be upset? We just want moshiach whoever he may be” or other attempts at misdirection.
The answer is “no”. He is not the Messiah, nor will he be, because he is no longer alive and that is the mesorah.