Untrue.
> It's the first programming language taught to every freshman Computer Science undergrad, everywhere in the world.
Except where Python is used. Or something else.
> Even most die hard Rubyists know how to write Java.
Well, a lot of the move to Ruby (particularly Rails) was a reaction to perceived issues with Java, so, yeah, Java skill is probably overrepresented in the Ruby (particularly Rails) community.
> Who in the world teaches PHP?
Judging from a quick googling, plenty of places teach PHP.