Well, maybe the shooter wouldn't have killed himself so early on if there had not been armed police there to force his hand. So probably, IMHO, their being there DID go a long way in stopping the shooter and definitely saved a lot of lives.
Another point, I'm no expert, but perhaps in an armed confrontation police do not really know who shot whom, i.e., whose bullet brought him down.
I think you are a wee bit to quick to defame the police officers involved. IMHO you can't get past the fact that those police officers put themselves in harm's way to stop the carnage. And no, I don't believe the officers were "too stupid" to know an autopsy would reveal who shot the shooter. They know very well that an autopsy will be performed and ballistics checked. And no, I do not for a minute believe that officers were "so desperate for hero status" -- they were doing what they are paid to do, getting between the public and a crazy.
Why do you have such a you-know-what on for police officers?