I think one of the big complaints about the gendered pronouns is that there's no established social path for this. How do you predetermine the preferred gender pronoun of people? You should try a social experiment--- you should ask the preferred pronoun of everyone you interact with today. It'll be awkward, and it might even get you punched.
Conservatives are saying: "hey, it's ridiculous to try to create a law about this, when it's possible to break this law in a truly innocent way."
coffeefilterbrain, I'd also just like to point that we have no law against calling someone the wrong name, and it's generally regarded as a childish thing to do. So I think conservatives feel that SJWs are trying to apply a legal solution to a problem that has a social solution.
I'd say that's definitely a complaint, but a minor one. The bigger complaint is the Orwellian implications of language policing, though the person complaining might not reach for the word "Orwellian" exactly.
It would also be annoying if my preferred pronoun was "sir" or "his/her majesty". That's an absurd example, obviously, but it's not entirely up to individuals to control language in their vicinity.
So? I don't have to call you anything. I can call you Bob or Samantha or Dingus O'Frankenstein. Legally you can't do anything about it.
They could have a protest where every person is called by their opposite pronoun just to show how it feels.
That said some trans people seem to want to introduce entirely new pronouns that didn't previously exist. That feels like overreach to me. Changing such a basic part of the language by force is not something to take lightly.
Edit: to clarify, I would not support such a law myself!