I'd imagine for some, the problem is being reminded they too can choose. And they've had the option to choose for a long time.
Honestly, that was my biggest issue the idea of asking other people their pronoun was sort of a trend (at least according to the rightwing media? idk; I've never once seen a person ask another person their pronouns in IRL). For some reason I never wondered why I, as a "cis man", I'd be afraid of such a question (especially since I was the type to like when people mistook me for being gay, so it wasn't like I was afraid of having my "masculinity questioned" or was anti-LGBT).