I witnessed the event. What robot999 says was true and did happen. The Sargeant at Arms did in fact state that no one with shirts expressing a position in favor or opposition to the bills would be allowed in the hearing chamber. He said he had asked others to remove their shirts.
I pressed the S at A to explain how the oath of office was a political position since every elected official and officer of the government takes the oath.
I walked out of the hearing when I heard the bill sponsor explain that the legislature could effect reasonable regulations that restrict guns.