Or he could be lamenting that the games themselves are not open source, but I haven't heard many of even the most die hard OSS evangelists suggest that AAA gaming content should be open sourced.
It's not as good as open source but let's be real, you'll never get AAA open source games.
Games don't need to access personal data (such as contact, phone number, photos, files, private messages, etc.) so with strong sandboxing I guess it could be a okay solution privacy-wise
https://github.com/flatpak/flatpak/issues/3797
"Recent versions of Steam can optionally put each game in its own container, using a Flatpak-derived tool named pressure-vessel."
Free software philosophy (the "F" in "FOSS") allows the art and data files (levels) of a game to be proprietary, while keeping the code open-source. Sell the game itself, code comes for free.
https://www.gnu.org/philosophy/funding-art-vs-funding-softwa...
Though ironically that means I can't use the new Proton runtime thing ("Soldier runtime" I think?) that sandboxes games via user namespaces, because my distro doesn't build the kernel with userns support so it would require me to give the Docker container more privileges.
[1]: https://github.com/valvesoftware/steam-for-linux/issues/3671