If you consider the public square “government”, government has no business with any religious symbols either.
If however you consider the public square “the people”, then you allow the people their freedom of speech, so long as the speech is not incendiary.
And if it is incendiary, you handle it through the process, not by having a legislator sneak in and tear it down.
A mob could have shown up and torn the sign down. I know that sounds counter-intuitive, but inciting mob violence would have proven that the sign was incendiary.
Do you understand how stupid we would look to past generations, when we write stuff like what you've written here, when we act like the idea that atheist Christophobes insulting people isn't admirable is the same as putting government in charge of free speech? Good grief. Moreover, I will repeat that there is a clear difference between the government opening the floor to any religion to promote their message and opening the floor to a message that is specifically designed to denigrate the others. One is pluralistic and neutral, the other is de facto hostility.
And if it is incendiary, you handle it through the process, not by having a legislator sneak in and tear it down.
I never endorsed it, I said it's silly to talk about respect when you have the state welcoming a sign that responds to symbols of peace and humor with unfounded attacks.