Hmmm...I dunno. I agree with the money thing - but I'm on the fence about the releasing it part. I mean, I think that all the extensions/addons for open-source systems should be free. I mean, I develop themes and extensions for other OS systems also and I like to see all that work go to use for free.
However, I can also see if a client needed something that I couldn't provide for their OSS and I would want to pay a third party to take care of it. The client might not be too happy having the extension they payed for given away for free.
So I guess my vote would be "Yes" for the section, and "Maybe" for the rules going along with it (if any)...