From the opinion piece:
Last year, I pointed out how many big publishers came crawlin’ back to Steam after trying their own things: EA, Activision, Microsoft. This year, for the first time ever, two Blizzard games released on Steam: Overwatch and Diablo 4.
Why would they have to open source anything? Just because it’s running on Linux doesn’t mean it’s OSS or even F(L)OSS. Steam isn’t open source either.
Not to mention that open source software can and sometimes does contain spyware.
That seems allot more like a one-off, a one time thing.
Also, anyone can view the source code for the open source product.
Nobody with two brain cells says foss can’t have spy/malware. What’s true is only that in important projects, it is very likely it will raise flags very soon. For example, see your link