tate did not get his hands on it until *after* jennings caught the ball. in fact, you can see tate try to get a better grip after jennings is coming down to the ground. the rule is that if one player (jennings) gains control first, the other player cannot claim possession.

all that being said, i did not expect the refs to reverse the call once it was ruled a TD. that would have required an understanding of the NFL rulebook which they did not exhibit throughout the game, so it's no surprise to me they would not overrule themselves after blowing it so badly to begin with.