I have thanked the opening poster. Why? Because every Muslim that is protesting in a peaceful way, is one less person that is out there, burning a tyre or a flag, rioting or killing because of something 'blasphemous'.
Of course I am not signing this petition, the nature of such a proposal is irrational and goes against anything I stand for. But the efforts should be commended.
If one is optimistic you could see this as a first step towards immunization, a point where religious people do not get bothered if someone attacks their religion, be it criticized or mocked.
Many Muslims are in a phase where Christians were many centuries ago. They react violently to perceived insults, issue death threats and destroy property in order to silence those who supposedly are attacking their religion. Most Christians have passed this phase.
The next stage would be were religious people protest in a a civilized manner. Write letters, boycotting , signing petitions, hold peaceful demonstrations and these kind of things. A few Christians and Jews are still in this phase, but these groups are extremely tiny and don't harm the societies. They are perfectly legal ways to express your discontent.
Finally, the next phase would be where criticism or mockery does not bother you, where you simply choose to ignore the (perceived) harsh comments or expressions just as most Christians and Jews today do.
This is a step which most Muslims, or at least many Muslims, still have to take.
This could take many centuries to come, but it will eventually happen. When these Muslims will realize that their way of thinking is flawed, the people that were out there behaving like they were personal custodians of Muhammad or Allah, as if those two entities could ever have been harmed verbally or physically, that will be the day when Islam will have won a great victory against all those 'blasphemers' aka the radical elements among Muslims that thought that Muhammad or Allah needed human protection, terrorist attacks and bombs in their name for being 'harmed'.