Based on what he posted, either he's doing an extremely superficial comparison or he's done a proper one and realised there is actually not a lot in it when talking about modern languages.

Fair enough, he wants to continue to use Perl because it's familiar and there aren't really massive advantages to using the other languages, that's a fair point, but state that as opposed to having a tone that suggests Perl is a better language than the others, or at least back that up with something quantifiable.

On the other hand, Perl (when comparing php, python, ruby) would be last on my list because it requires the most effort to learn and get familiar with the syntax and I don't think the extra work required to learn Perl is worth the effort, because again, I think you'll actually be alright with the modern versions of all the languages.