"[they] were in a no-trespassing area and refused to leave"

The article does not say why the area was designated as such. My guess would be for security reasons. Every president (with a few exceptions) has had to worry about looneys trying to kill him. Secondly, I doubt that the decision to eject these people was made at any higher level than the handfull of security persons directly involved in the incident.

I don't have a source, but I remember hearing about a fellow who attended a showing of F9/11 and began to loudly argue with the content of the movie. He was promptly arrested, and recieved his Miranda rights and a court date. Afterward, he called in to the Limbaugh show to complain about his rights being violated and Rush essentially told him that he was asking for it, and to shut up and take whatever the Judge gave him.