He approves of developers selling GPL exceptions. He doesn't approve of buying GPL exceptions*. It's a subtle point.

(The natural corollary to this is that if the Element/Matrix folks—or anyone—were to ask you for a CLA excepting them from the project's own open source license, then you could/should feel comfortable kindly requiring them to pay you for it—a response which should be the default in the open source world, although it unfortunately is not.)

* i.e. so you can make proprietary software