I understand the visceral reaction there, but OWASP is a nonprofit foundation, and conferences cost money to host. They were attempting to make the conference as cheap as possible by getting volunteers instead of paying people for whatever work they could, I'm sure.

If this was a for-profit company, I'd completely agree with you, but it's not.

So, like any other instance of this (in academia).

I was going to say: that describes Usenix, too.