The "New Atheists" have a real image problem. They are seen as immature whiners.
Blasphemy Day only strengthens that image.
Albert Mohler has some excellent commentary.
The irony is that Blasphemy Day is largely aimed at Christians, who (again, largely) make no claims that blasphemy should be illegal or punished (it was in the past, but few argue the laws should remain).
Of course, in a Muslim nation, no one would dare do such a thing...
Yet Blasphemy Day claims to be against all religions.
At the same time, it is a Christian notion of rights and equality which makes it even possible.