Agreed. I won't go as far as he does, but I thank him for making a stand. As far as the user makes an informed choice, I am not against selling proprietary software. Still, God kills a kitten every time a proprietary license is sold.
Even if it's my grandma's startup selling it. Even if it's the girl scouts selling it.
Seriously, when your user knows and willingly enters what has a good chance of becoming an abusive relation (depending on your upgrades, being unable to migrate their data, forcing you to support ancient versions because they don't have the money to upgrade), I believe it's fine.