The Problem With Hulk/The Improbable Hulk

After reading the first two issues of Marvel NOW's Indestructible Hulk I was definitely impressed.  However, I keep stumbling on the same problem. This is the same problem I came across at the end of Watchmen when Viedt would potentially rule in polotics even after killing millions. Banner is trying to reform and make better use of himself and the monster in side of him by enlisting in S.H.I.E.L.D and is also making attempts to change global issues such as the water crisis. Now, how can S.H.I.E.L.D or even the world trust someone who has killed many people and has the potential to kill many more? In the second issue he makes friends with Iron Man by bringing him on a dangerous mission to the Himalayas and then saving him from an avalanche and later an explosion that Hulk created. This would have been a great issue aside from the far-fetched notion that Tony would now trust Bruce because he saved him from a predicament that Banner created himself. I get that that is the whole Hulk schtick; learning to control himself, but I would want a little more evidence that he is fully stable before I trust my life to him.