I think he saw it as unintentional, I thought Dunk was bringing his hands down as he felt he was about to collide with the Ipswich player and it was a protection thing, and happened to make contact with the ball. As handling is only an offence if it's deliberate, that wouldn't be an offence and thus no penalty. A generous interpretation, perhaps, but that's how I read the situation and so think perhaps that's how the ref saw it, too.
Regarding the penalty, on the replay, it looks like Bruno is using his hip to push the player away, which is soft, not always given, but still one of those penalties that Dermot Gallagher would defend saying "I can see why he gave it" (meaning, he wouldn't have given it, and wouldn't advise refs to give them, but it wasn't so bad a decision he is willing to publicly criticise one of his refs).
