Turns out this wasn't too difficult to implement

If a player isn't moving in both rotation and movement they will be marked as inactive, being inactive means they can do anything and still be marked as AFK when the timer reaches TimeToAFK. If they do move in both location and rotation this won't affect them, this should mean little to no false positives. Location and rotation are checked every 5 & 7 seconds and the two measurements are compared.

This method should detect most AFK machines and mark the player as AFK as if the machine wasn't doing anything. It is up to your permissions to deal with the player but the use of an AFK machine shouldn't stop them from being marked as AFK by AFKPlus