Who switched the comet off?
Ok, not trying to push any sort of alien signal cover up conspiracy theory, just a couple of questions that the article didn't address (ok, I'll admit I've not read the full paper, does that explain?)
From memory, there were two dishes pointed at the same location, slightly offset. If it was comets, surely the other dish should have picked up the same signal a couple of minutes before or after? Or is the signal not constant but changes as the comet spins? (for instance)
I gather the scientists pointed the dishes back at the same point and surrounding space repeatedly afterwards without picking up the signal again, surely comets don't move sufficiently fast to be nowhere near the next night, or even weeks later? So why was nothing picked up?
It seems most likely that if a comet that has since been shown to be emitting a signal at that frequency was in the same place at the same time, it's probably responsible. But doesn't answer those questions.
Just looking on wikipedia, the article on this event references this paper but says it doesn't answer the first question, and says (but cites no sources) that Ehman and his colleagues think it highly unlikely to explain the signal. Not that they're biased.