John, considering how many times I injured my groin while running track in high school and college, I agree with you there. However, they had TE on the sidelines moving around (at least that is what i saw from the tv angles). It would have been smarter for them to keep him in the locker, but should JP have went down, they may have had to put Trent in. Again if they chose to put Hamden in and he got hurt, surely they would have put him in before putting action jackson in as emergency QB.
As the expert on injuring the groin. If TE has any toughness and the injury is moderately painful or less, he'll be in. If this is severe (like when Hasek was out for over a month, which I don't think it is, as he was back on the sideline and didn't limp off the field), he will be out a couple games, easily.