So what happens when Python and Java come out with their own archives? CJAN's on its way and a Python archive will be coming shortly as well (and they already have a good number of modules). Given the number of developers, I doubt they'll have much trouble finding contributors.
CPAN's advantage is going to be quickly reduced. If you want to prove Perl's superiority, why not focus on the actual language designs instead? Who knows, maybe the discussion will lead to improvements in all of the languages. Simply saying "Perl's better because it has more modules" leads me to believe you don't know Python well enough to comment on the actual language.
Preaching to the converted isn't much of a challenge either. If you really want a good debate on the subject, bring it up on a Python mailing list (in a nice non-flamebait way ;).