There are no words to describe what a shitty person this is. I bet he's also a scab in the current Reddit protests trying to kiss up to spez for some crappy Reddit merch.
Go on Kijiji, buy a shit laptop, do a fresh Linux install, go sit outside a McDonald's or somewhere with fewer cameras, get on free WiFi, rip it and upload it, and toss the laptop.
I work in the games industry, and have extensive knowledge of NDAs that may or may not be attributed to unionization efforts. If you find a random disk somewhere and the contents are confidential, you are not subject to the NDA. They can ask, and even sue, for the property back but it's not a guarantee that they'll win. There are cases like this that have gone both ways.
The owner of the disk could have anonymously leaked the contents, sold the disk, or anything they wanted with it. It doesn't matter because in general, if the disk was legally acquired then it's their property to do with as they please. Leaking the contents is the only legally questionable thing that the owner could have done with the code.
Don't even think of mentioning making games libre software or you'll get attacked for endangering people's livelihoods for "selfish fanatical ends" and forcing game devs into "a vow of poverty and piracy." It's not worth it to these people.
If the game is something people really want to play, having the source code makes it a lot easier for someone to make the game work on modern operating systems, and possible to port it to ones it didn't originally support.
The source code of a program is like a recipe and list of ingredients. If you buy a coffee from Starbucks, you get a coffee from Starbucks. You can't easily change the beans used, the brew temperature, etc. With the recipe, you could brew your own with slight differences, or make coffee from scratch knowing everything that's in Starbucks coffee. With the source code for a game, you could change/mod anything. FPS unlock mods, ports to other platforms, and much more. You could make your own game, and make it better knowing how some systems work in another game.
Some games have their source code leaked, in which case it is illegal to own, redistribute, or learn from the code. Although it'll usually still happen, it's much more "underground" than games where the source code was reverse engineered. Reverse engineering is like buying a coffee, tasting it, then coming up with your own recipe. Having your own recipe almost exactly identical to the original still allows you to make changes easily, but it's not illegal, as you wrote it, and are allowed to share your own recipe. Some older titles like Super Mario 64 have been fully reverse engineered, and ported to every possible platform, with multiplayer mods, FPS unlock mods, etc.
So the source code gets turned into a .exe (or equivalent) when it gets compiled right? What stops it from being decompiled? Do the developers add in some kind of cipher? Or is it just that working out what the low level code does in the exe is very difficult?
So, especially with PC games, software is compiled using an IDE/language and runtime environments. That last part is why games stop running on newer versions of windows, and it's especially why older games can't just "be ported" to consoles, mac, etc. Once you compile a program, it's like etching that program into a stone called an executable/extension(DLL). If you want your program to run on anything other than the old compatible hardware using their runtime libraries, you gotta have the OG source code in order to recompile. Blizard North had a liquidation sale way back and the source codes to their projects was in it. They've been scrambling to get it all back to make remakes/remasters.
I recently found a fan recreation of a RTS game from around this time called Lego: Rock Raiders (The remake is called Manic Miners if anyone is interested). Would’ve been really cool to have similar fan remakes for StarCraft and Warcraft but with some of the actual code to port the engine up like GZDoom.