His behavior is not inconsistent with the ending of the Norton movie, where he smiles as he realizes he can now control his Hulk-Outs.
Arguably he has worked out that when he changes voluntarily, he retains more of his own self as it's not rage driven in the same way as an unintended episode. The change on the Heli-Carrier is not intentional and driven by pain and rage, he does try to control it but can't as Banner has probably suffered severe, possibly catastrophic damage, similar to the bullet in the mouth and the change is to save his life. However as it's caused by pain and rage, the Hulk is more mindless and attacking anything in sight, just as the pain attacks Banner. Arguably the thing that saves the world is the security guard.
Banner the man as portrayed by both Norton and Ruffalo reacts well to kindness. In Norton's film, from the factory owner, the girl next door who loves him, the guy at the Pizza place, even Lou's security guard... all show him kindness and respect and it lifts him. Conversely those who do not, suffer at the hands of the Hulk. With Ruffalo this carried on... He likes Widow for "asking nicely", Cap for his "only word I care about" line and Stark for his "banter" and not hiding from the Green Monster in the room. Even when he has the scepter and is getting angry, Cap asks him nicely to put it down and he does. Why is the guard important?
When he falls he is again shown kindness and respect, perhaps the most important of all. They guy could have called the Police, shot him ran a mile but he stayed till he woke up, made sure he was OK and didn't judge or treat him badly for it, he accepted it and helped him with the clothes and the motorbike. It's a shame the extra scenes were cut with Harry Dean Stanton. But the point is the Hulk that shows up knows that not only are the people he is fighting with respect him and are worth sharing his secret with, but that the people they are fighting for are worth embracing being the Hulk for, more so than when he fought Abomination. He retains control because it's the conscious decision to be the Hulk rather than a reaction and his "angry all the time" line is his way of telling the Avengers he KNOWS whats coming this time, which they won't have seen... only the rage filled uncontrolled version.