He’s a libertarian. During the BLM protests, Valve workers wanted the company to make a statement one way or the other, and what the company ended up doing was giving each employee a bonus that they could donate to something if they wanted to.
This video, where they directly interviewed (anonymous) current and former Valve employees. Unfortunately there don’t seem to be any articles on the bonus specifically.
I found a YouTube link in your comment. Here are links to the same video on alternative frontends that protect your privacy: