Not a defense, just an observation. Conservatives aren't any more known for their defense of free speech than liberals are. It depends on what the speech being targeted is, for both sides.
As for the unconstitutionality of this law, or course it is. But why act like this law is THE test? Congress passes laws every year, and presidents sign them, that are unconsitutional. The Supreme Court has already ruled on the speech issue presented in this law, and it WILL be struck down. Bush is fully aware of this, as are the politicians that passed it. This is all about politics, for both sides.
As for myself I would much rather that the President take an "unpopular" stand, based on Contitutional PRINCIPLES and not brush it off on someone else (SCOTUS)
David