No he didn't, which is kind of understandable because he's almost solely responsible for the loss. Both Denver touchdowns came off of Cam Newton fumbles. Newton's a Super Bowl quality quarterback; his 50 touchdowns during the year prove that. But he turned in the worst game of the season last night, maybe the worst of his career. And he was no doubt feeling humiliated and angry with himself and knew he'd let his team down. So no, his actions weren't excusable at the press conference. But I can't think of any other quarterbacks out there who would likely have acted much different had they been in Newton's place.
Russell Wilson. See: SB 49.
I can think of thirty-one of them.
Russel Wilson last year, for one. His pass near the goal line was intercepted, and the Patriots won. It was a horrible moment for him. That pass lost the game. His press conference following the Superbowl loss was full of humility- he took full responsibility- and praise for his teammates and the Patriots, with a positive message for the next season. He acted like a man, not a petulant child.
How about Payton Manning after losing what most thought was his last chance at another championship after getting routed by Seattle? There are a lot of similarities, Denver that year was a record breaking offence that ran into an immovable Seattle defense. Did Payton have a tantrum? Maybe when he got home, but in public he was a gracious loser.