I said "if" the Tarot card was left by the sniper. I don't know and I'm sure you don't either. It's possible that the killer(s) are muslim terrorists, but I personally think it's unlikely.
Or a piece of disinformation to confuse the public.
I may be wrong, but I don't believe that the Moose-in-the-headlights has formally acknowledged the existence of the card, or what it actually says.
Given that he seems to have a vested interest in protecting practitioners of the Religion of Peace from any community-based profiling, and that this is the one piece of exculpatory evidence, why not release it? Maybe Beavis's Mom will recognize the handwriting.
Perhaps the card doesn't exist. Or, is the quote "I am God", just a mistranslation from the original Arabic?