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 --
there is a  Copyright Clause argument. 
( z1 argue :ARG1 ( z2 law :name ( z3 name :op "Copyright" :op "Clause" ) ) )