A crime is a crime even before a judge rules over it. Sure, innocent until proven guilty, but most people know when they're doing something wrong and then don't do it.
Of course, this is a lot more grey area for copyright violations etc because it's a civil matter.
It's quite dangerous to make unsubstantiated comments and assumptions on US copyright law without the proper research.
Valve still owns the copyright to the game and just because they won't do anything now does not mean it is legal to redistribute it without their consent, especially when we know that the game is still being sold. [0]
They (Valve) reserve the right to enforce that and this site clearly does not have such a "license" and haven't disclosed as such. Why would you expect Valve to be in discussions with a 15 year old to redistribute the game for free?
> just because they won't do anything now does not mean it is legal to redistribute it without their consent
I don't think the parent comment is claiming it's legal, other than the (unlikely) chance that this is licensed, just that it's up to Valve to enforce and not really our concern. A lot of cool things (like the similar https://noclip.website/) are prima facie copyright infringement.