I'd wager a lot of them are saying that not only because it's fundamentally true but also because they're likely wavering a bit themselves.
It creates a visceral reaction when you consistently see people getting bullied for no reason other than for simply existing. I believe it's concomitant to anyone who's at least been raised with some modicum of principles to begin questioning their beliefs when they see not only stuff like this but so many other things that are taking place in our society that are antithetical to the beliefs the group they support pretends to profess.
Of course that doesn't mean they'll be "switching sides" any time soon — many of them have built their entire identities around it — but it certainly will cause them to begin questioning things. What will really make them begin to see reality is how media spins things such as this — or how they outright ignore it, because it doesn't fit with the narrative.
I don't expect much from such people, though. Most of them are too deeply saturated in the media manufactured hate that they likely won't even notice.