Let's consider this for a moment, and assume that the story is true. (If it's not true, then there's not much to say other than shame on them for making up such a story.)
At a tax-funded event where the leader of the country speaks, people who exercise their right to air their grievance are barred from attending.
I could understand if this were a private event. I could even understand (Though with much more difficulty) if they were actively threatening the President. All these people did was show up with a bumper sticker that offended somebody. I can't imagine that this is acceptable by the GOP, just as I can't imagine this being condoned by the Democrats.
I don't blame the GOP. Rather, I'm upset with the people directly invovled in this incident, and I hope that, if this is a true story, that they get their comeuppance. I don't like trampling on liberties.