No, there was no trigger. There was a digital clock taped to the tube with wires running to it, but the 4chan guys figured out which model the clock was and it turns out not to have an alarm function which means it probably couldn’t have been used as a trigger. It was just there for appearance sake. To me the bombs come off as an almost comical parody of the real thing. He even put a sticker on them that reads “git ‘er done”. Pretty obvious that he was trying to scare people, not hurt or kill people.
Sounds right. The FBI is not observing the fake-bomber's right to self-expression. :)