Perl is really easy and quick to dev with too. So is ruby. That's not the point. Powder is written in C now, so why change it? Give a good reason to change from something that already works, not a good reason why one language is better than another.

Personally, I'd go with C++ btw, it's object oriented so you can split the physics from the drawing some more. But C's fine too. No need to change to something totally different that no one even knew about till a few hours ago.