Neither offends me in the slightest.
To equate the Koran with a flag is deeply insulting.
I guess the question to ask Clarence would be whether he thinks burning a bible is worse than the flag, or the same. And if it's worse, then why isn't burning the Koran worse as well.
The two aren't really comparable actually, the status of the Koran in Islam and its nature has reasons why burning it would be far more offensive to Muslims than burning the Bible is to Christians, though even if I were Muslim I doubt I'd get too bent out of shape over Koran burning. I see being offended by desecration of any symbol (outside of the stupidity and nature of it just being real life trolling) to be essentially idolatry.