No, but that's the Copyright Clause argument, and it seems to me you're saying, okay, we then apply that in First Amendment analysis, which allows us to make a coherent intermediate scrutiny argument. If we don't accept the Copyright Clause retrospectivity argument --
the Copyright argument will be apply in the  First Amendment analysis. 
( z1 apply :ARG1 ( z2 argue :ARG1 ( z3 copyright ) ) :ARG2 ( z4 analyze :ARG1 ( z5 law :name ( z6 name :op "First" :op "Amendment" ) ) ) )