You forgot this:
You don't receive some software derived from software previously licensed under BSD. Let B be the set of all things you can do with/to the software.
You do receive some software derived from software previously licensed under GPL. Let G be the set of all things you can do with/to the software.
B is the null set, therefore B is a strict subset of G.
Hence, G has a more liberal license than B.
In the end, the discussion of "which license is more liberal" is silly. Each license yields different freedoms to different groups of people. Use whatever works for you, don't use what you don't like. Advocate licenses you'd like other people to use. Just don't oversimplify the discussion with simplistic logical fallacies.