Daniel Greenfield says it is true and that is good enough for me!
So I wanted to see who this Daniel Greenfield is and one site has him outed as this:
http://www.loonwatch.com/2013/01/islamophobes-spencer-and-greenfield-push-fabricated-mohammad-al-arifi-fatwa-story/
So with that in mind maybe you should do some checking up yourself.