Now that I've done a little research...I understand. If you apply for, and receive a press pass...you are expected to behave in a certain way. You temporarily put your personal beliefs aside and are there to report.
Your free speech rights are completely protected when you are honest about your purpose and intent. The flip side of this would be...how would we like it if the Washington Press Corp, or the Iranian Press people heckled our side every time they held a press conference? In fact, lets be specific: Anyone here upset when Cindy Sheehan was arrested before the SOTU because she had a message on her T-shirt that was clearly inappropriate?
Anyone upset when Code Pink protestors where removed from the GOP National convention during the President's bigs speech?
Just because we happen to agree with her, does not give her the right to do it dishonestly and against protocol. It's called civility.