With the way the Ravens defense was playing, it may have been a moot point. Not sure.
And the Jim Harbaugh one was odd as there was no evidence to suggest the ball wasn't caught. I saw that as a "why not" challenge since he had timeouts to blow and it was a 4th down play.
Coughlin has made a few stupid challenges this year that I have seen including one today...there does not seem to be anyone that is truly good at this stuff...