Frankly, this isn’t anything to do with the government anyway, nor should they be getting involved
It kinda does though. The only way you’re going to force companies to keep their old games available is through laws. Companies will only release source code when they take down their online games if legally compelled. They will only release source or keep on steam old off-line games they don’t want to keep up if they are legally compelled.
And honestly, it seems like the bare minimum to give the community the resources to keep playing a game when you’ve decided as a company it’s too old and you want to move on from it.