Meh. That's a whole lot of (metaphorical) ink spilled over the difference between transphobic actions and being a tranphobe as if that's a meaningful difference. It's not. It might be better for your optics if you're trying to change behavior by making one approach over another, but it's not even a semantic difference, it's a tactical difference. And since he's not in this thread to worry about how he reacts and which approach is likely to change his behavior, I couldn't possibly care less about which tactic feels more effective. It doesn't matter how much he's on the right side of other naughty word, he's on the wrong side of this one.
At best, it's the difference between being stupid and acting stupid. Sure, if you did something stupid once, maybe you aren't stupid. Maybe you just made an honest mistake and we shouldn't keep calling you stupid. But if you do something stupid, then insist on continuing to do it for years, then defend it later and claim it wasn't stupid... yeah, I've got no problem calling you stupid about it. So yeah, I've got no problem calling Alexander a transphobe about this.