Had a few instances where a non-PUG team mate had to go afk for a while... then the remaining players face the dilemma: Kick or not?

If you don't kick, then the party cannot proceed. But if you kick, then a guild mate / friend will be forced to solo. He/she may or may not be able to handle it, so you may not want to do this to a friend/guild mate.

Sometimes people do need to go afk - like a sudden need to use the toilet, or answering an emergency phone call.

So I'd suggest treating knights who used the /afk command as disconnected, and teleport them to the group button. This allows the party to move on, at the price of the having to protect/revive the afk knight.