I'm putting together the last few bits of that Cullen FAQ and I just wanted to verify with other people and not just project my own feelings onto it... It's not really a stretch to suggest Cullen respects Hawke regardless of what side of the mage/templar debate they are on?
I am on the "Why did he let me go, I sided with mages" bit.
I know that we don't really know what was going through his head at the time (about 10 different things probably) but I'd imagine his respect for Hawke may have been a deciding factor in why he backed off.
I don't think "afraid to die" is exactly a valid reason to put either, since he wasn't sitting in the corner sucking his thumb during the Meredith fight. I know a lot of people suggest that being a reason, but eh.