“Chabad does have Seudas Shlishit in their shuls.”
Full blown lie. I talked to a Chabad rabbi who said the the overarching organization doesn’t even allow an individual Chabad house to do it even if they wanted to for their non-Chabad members. Their reasons probably being that Chabad minhagim would be lost in their shuls if they started compromising for everyone else.
“Not eating before davening is minhag, not Halacha.”
Also a lie, or maybe just ignorance. It’s an issur d’rabbonim brought in the Shulchan Aruch. Nobody has ever paskened otherwise. Chabad simply ignores this halacha without justification other than saying it’s their minhag.
“The Rebbe was against people who made such claims.”
Source?