You do not need Kernel level access in order to cheat. Bungie wants kernel access in order to implement a system which can check what processes you have open in order to prevent you to cheat, because they couldn't figure out another way to stop it, but cheats exist in Windows and have allways existed. In fact, I think right now it would be harder to cheat on Linux than on Windows, considering software like CheatEngine exists.
All this does not even matter here tho, because the goal of that Anti-cheat software is to prevent the offline user from cheating, so that their online interactions are legitimate. Here we are talking about an MMO which runs must of the logic and cheat detection on the server, it has nothing to do with the client. Whatever cheat you would do in the client SE would probably notice and ban your account as you are allways online, so again, Kernel access has nothing to do here.
And in any case the fact that linux kernel is open source does not mean you cannot make any privative kernel module, it's just if you wanted it to work on every linux distro, or in this case on any linux kernel you would have to either provide the source code, which Bungie obviously wouldn't do, and i totally support they don't (giving someone the source code of an anti-cheat software would make people figure out how to break it), you could also provide binaries for specific linux kernel versions and it would work without an issue, making no difference from Windows. So i totally don't see your point here at all.
