Just as Ds, Libs, & Progs seem not to have anticipated their special interest groups coming into unresolvable conflict (e.g. Enviros vs. the UMW), they seem not to have realized that their Prog with-us-or-against-us-ultra-purity thingy would similarly bring different interest groups into conflict. Nor anticipated that Progs' Victimier-Than-Thou mindset would turn inward.
Here, we have the latter two: police have participated for years in many/most "Gay Pride" parades, but now that crosses BLM, who hate police; BLM is claiming the top spot in the Prog Hierarchy of Victimhood, so the gays need to bow to BLM's wishes and apologize abjectly for not having booted the police out of "Pride" events without being told.
2 or 3 years ago, the GLBTUVWXYZ people were at the apex of the Victimhood Pyramid, but the Pulse nightclub shooting a year ago (the character of which Libs & Progs still deny) and now this stuff (one of the first such disruptions I heard of was in Toronto, Canada, so it's not just nationwide) have taken the gays well down from that apex.