Because they aren't really denouncing anything -- they are simply practicing the art of Taqiyya.
Based on alot of responses here, I would say they are already successful, even w/out the march.
Have you even gone to their web site? This is what they say about terrorism:
"Our Positions
Terrorism
The Free Muslim Coalition Against Terrorism believes that there can NEVER be a justification for terrorism."
That's not a denouncement?