“In fairness, for 24 hours, he was a muslim on Free Republic.” I think the truth of these suppositions is pretty close to the following: If something is ACTUALLY politically/terrorist motivated, the chances are strong it's going to turn out to be a Muslim. However, the number of loony/loser killings in a nation of 300,000,000 is, unfortunately, sufficiently large that out of all the multiple killings, most of them are going to turn out to be non-muslims, however much some may wish it to be otherwise.
The best advice is to let it shake out at leat a couple of hours before jumping to conclusions. Once a perp is ID'd, then you can go to town. Viz, the Salt Lake City shooter, who was a Muslim, though also apparently a young loser, v. Omaha and this guy, who sure seem pretty whitebread, based on all of the evidence so far.