It's said that you can tell a lot about someone by who opposes them. In the case of liberal pundit Bill Maher - a man who called America's actions cowardly in the wake of 9/11 and who mocked WWII veterans who wanted to visit the monument built in their honor - I wear his disapproval of me as a badge of honor.
We have testimony saying, and I think common sense also dictates, that in a failed state like Syria, you don't have any government information, police reports to rely on to vet somebody. So there's no way to do a background check from somebody coming out of Syria. There's no way we can find out whether they're safe or not.