This penalities only apply when you raid >active players<.
You won't receive penalities anymore when robbing a player who is at least 28 days afk, even if you should get a penality.
You still get penalities at 7+ days afk.
You can check that yourself when you rob a 28+ days afk person because it a) is in the battle report and b) this attack won't be added to the list in the "trade"-tab.