She was probably thrown out because they felt they had to be even handed, throwing Sheehan out. Either that or the guys who were told to throw out Sheehan were lefties, and they wanted to voice their opinion by throwing out "one of theirs" in retaliation.
She was tossed because rules are rules. Even the tourists are warned about it when visiting the galleries.
Any form of protesting inside is a misdemeanor. It's bad enough the democrats get away with their behavior on the floor, but can you imagine the circus it would be if anyone was allowed in with their pet cause banners and signs?
Karl Rove.