The argument holds for general software, but there isn’t a viable business model for open source games. No point in telling people to get games elsewhere, there is no elsewhere other than games made as a hobby.
As a parallel: Here in Brazil child-targeted advertising was banned on TV. Cartoons and kids’ shows, without funding from ads, disappeared as a consequence. If people stop paying for proprietary games, they won’t magically come out of elsewhere: the industry will simply die.
For small indies Itch.io is a thing, but donations are not going to pay for the next GTA.
The malware was detected and removed even though it’s closed software… so one could argue open source is not necessary. You could also argue that DRM-free games are good enough.
I think this argument makes sense for firmware or operating systems… but I’m not sure it applies to games.