This is so funny because rust has one of the worst cheating situations and majority of their players are windows users, and theres lots of games that have anticheat that allows linux and have notably less significant cheating problems like marvel rivals. in reality rust doesn't take cheating very seriously because if they did they would have more server side software that detects illegitimate behaviour like tons of other games do successfully...... even most popular Minecraft servers have better functioning anti cheat that is completely server side than rust has while getting kernel access to your pc. its pathetic and lazy development tbh and this entire post from them reads like such extreme cope....
You're almost correct, but a sound bouncing off a wall sounds the same as something beyond it, or coming from a slightly different angle, just like how visually a reflection is "beyond" the mirror. Sure, you can try to calculate that back to the original location, but that's not very accurate, nor does it tell you the origin of the sound, could be an enemy, could be a friend, could be random low sound spawns sent by the server to bait cheaters.
For the threshold I think it's a lot smaller than you think, while a wall hacks that shows an enemy that will become visible the next frame is useful, it's a lot less useful than current wall hacks.
As for the audio, you can absolutely randomize stuff enough that it's useless to hacks but useful for players, because no person will hear a sound and know the exact source of it, only a general direction. Hell, most games don't even do proper wall bouncing or other sound mechanics that would allow humans to pinpoint location in real life.