Bill,
How can you say the rule is very clear and then say that unless Player A makes his move often he is unlikely to be penalized? He left the table before Player B went all-in. I will assume the action was head to head. After the all-in, Player A gets 160K returned to him and the cards must be tabled, correct? Who tables Player A's cards if he does not return immediately? Don't tell me it's the dealer, because no dealer should ever turn over a players cards.
Forget that bull about
"He is denying the remaining players the opportunity to get a read on him while sitting at the table." I see player's wearing costumes to hide their eyes and their beating hearts!
Now that's something for discussion.
If you leave the table, with action pending, you indicate a lack of interest in the game! You should be penalized just to discourage the same from becoming a regular occurrence.
Isn't that the purpose of TDA #30? Let's look at it again: A Player with a live hand must remain at the table. Why not just say: A player with a live hand must remain at the table until the showdown is complete!