I want to suggest Tripwire to implement this mutator as Weekly challenge, the gimmick might be head damage resistance corresponding to hat rarity. Plus it's a good exposure for zedconomy, because you see a wide variety of cosmetics in a single game, where you wouldn't see as many otherwise.
Thanks! Just tried it, It does work with the current version of the game and it's not whitelisted. One thing i noticed gorefiends aren't wearing any hats, I wonder if it's because it's the newest zed and it needs to be referenced in source code to have hats.
Unfortunately this version doesn't seem to work for me, i get connection failed upon trying to join a server running this version.