Man, what a bunch of whiners. You can get a TCAS RA without being in conflict. We get it all the time in busy airspace, particularly when traffic is coming in on a base leg to join you in a parrallel approach. If you guys wet you pants every time the TCAS lights up then please stay out of busy airspace. You won't make it to retirement age.
GA pilots flying in congested airspace are not an issue if they know what they are doing. The controller can tell by the initial call up if the guy he is talking to is a tool or has his stuff together. We can tell from the cockpit as well. Some of the international aircarriers you hear talking on the radio and see taxiing out of SFO and JFK and LAX inspire less confidence than most of the GA guys here.
UAL has some really weak pilots. They had a major screw up a few years ago on departure out of SFO in a 747-400. The F/O almost put it into the hill on departure when he couldn't handle an engine failure. If there is an error in this incident I would look to the UAL crew first, then the GA guy and the controller.