It's his program, he can do what he wants with it. If you don't want to pay the money then make your own irc client. There's this terrible idea nowadays of open source being cool and everything that's involves money being lame. Well sorry but we're not all so sad that we like to invent the wheel for ourselves over and over with everything.
Well, open source software and software you pay for are not mutually exclusive concepts. You can charge for open source software, I have, in fact I've written a couple of open source programs that I sold for something like $750 a piece. It's just, instead of getting just the .exe file, you also get all the source code as well. But it doesn't have to be free. Prime example would be Linux. Red Hat for example charges something like $150 for the OS, and you get the source.
So basically, you can have open source software that isn't free.