Modifying the game so that it runs offline is supporting the game. Three years after releasing a game, the devs who made it are usually long gone, busy on other projects, the libraries and framework used are out of date, out of support, etc. at that point making any change (or even building the project!) is a significant effort.
It's a "significant effort" only because it was made this way. You can design it to be easy hostable. It's just that there is no reason to do so currently. Stop killing games tries to give some legal reason.
