That would be fine, but it's inconsistent w/ previous behavior. For instance, the same "religious courtesy" was not extended to the Muslim teenagers he snipered as they tried to pirate a boat last year.
And besides, any good Muslim will tell you that Osama's (or Usama's) form of Muslim was an extremely perverted one. So why would they care if we did or did not respect him as a Muslim? They could have easily done a Walt Disney on Bin-Laden, and then had outside experts from several different Countries come and confirm that it was him.
Using political correctness as a reason to dump the body is just lame. Especially since thankfully you didn't follow political correctness to sneak in and blow the un-armed guy's head in half. Who really cares about political correctness after that?
My guess would be they didn't want to piss off the crazies anymore than they already did. I have no clue, just giving a possible reason.