I don't agree with the scummy thing John did, but the angle that he was attempting might be of interest from a game theorist prospective (not sure)

With 100k in the pot with a board of
KQ35
Holding AK for Top-Top!!

John has to call off his last 30k so he is getting about 3:1 on a call but with a rather polarizing move by his opponent.

John knows he is already going to call but has a strong feeling he is beat.

he decides to ask for the allin button with the caveat that he is not going all-in

he lets the allin button pass the line on purpose

If..
A.) His opponent points out John crossed the line, then John knows that he is beat 100% of the time.
if that happens..
A1) It is ruled as an all-in and he is eliminated
or
A2) The dealer or TD falls for the caveat mention earlier allowing John to give back the allin button and 100% folds his hand.

B.)Nothing is said by his opponent. That he wasn't call out for the line pass would allow him to comfortably call off his last 30k.