The interception slide was a terrible decision. Even if he doesn't take it to the house, he still flips the field for position--either to attempt a FG, or pin Seattle back after a punt. In a game like that, even an extra 20-25 yards of field position is crucial (not to mention potentially adding points!)
But after that, the play calling was atrocious. Run up the middle, no gain; run up the middle, no gain; run up the middle, no gain. "Gee, guys! Looks like we have to punt!"
I see this time and time again (it's worse in college ball, but still prevalent in the NFL). NO attempt to gain a first down. The best way to protect a lead is to make first downs! You have to at least TRY to convert a first down in that position.
GB got what it deserved the way they approached the game in the second half.