My point exactly - validation usually involves write permissions to put a challenge or something else as required by the protocol (ACME in your example). If I p

My point exactly - validation usually involves write permissions to put a challenge or something else as required by the protocol (ACME in your example). If I put the security.txt file there and certbot gets compromised, there goes my security policy. Putting security.txt up one level so only root (I.e. me) can update it allows me to keep .well-known writable by robots only.