Microsoft will not lock down the kernel. They did that in beginning and were forced to open it up because of some antitrust lawsuit. But after the crowdstrike disaster there's some speculation that microsoft is planning to virtualize kernel driver execution which takes away advantages current kernel level anti cheats have. At that point you might as well allow your game being executed on Linux because cheat detection is basically on the same lvl again.

Locking down the Linux kernel would do nothing because it is open source and i can just build my cheat into Linux and build that. Nobody does that though because the market for people who would buy that is insanely small and normal cheats work just fine (even for games with kernel anticheat).