Agreed. Why is the state offering plates that support one side of a very political issue in the country? Oh, that's right, because they are politicians and think they know better. And no, the state shouldn't get away with it even if they offered opposing views. This is just way, way outside the scope of a proper government.
Gawd, the mindset you have to be in to use taxpayer money to push your own [oppressive, rights-violating] beliefs. It's stoopid.