Comment by ChocolateGod

A game can start up native Linux binaries even when the game itself is running under Proton.

But EAC has a kernel driver and there's no real native way of doing that on Linux that's stable as Linux has no stable kernel API, and measured boot isn't widely adopted so a custom kernel can just lie to the anti-cheat module.

I really hope Valve work on this, whilst it would mean perhaps online play only run on SteamOS in an optional locked down mode, it's better than the status quo.