That’s not how I read it at all

By supporting work on a freelance basis for these topics, Valve enables us to work on them without being limited solely by the free time of our volunteers.

Seems pretty explicit to me. Valve is allowing some arch linux contributors to work freelance for valve and get paid money to work on the things they would otherwise be working on for free. This allows these contributors to spend much more time working on these things because they can treat this work as the-thing-I-do-to-put-food-in-my-mouth rather than something extra they would do on the scraps of time they have on the side.