As played, I am against the all-in shove...
I think this is an ICM decision but I don't want to do any of the math and we don't know all of the payouts. Just remember every chip is worth something in dollars and cents. Er, pounds sterling and... something else!
I often make silly mistakes late into tournaments. I am seriously trying to get over myself here because it is high time for me to take one of these large, live MTT events down.
Figure out the ICM and use it as a learning experience. You'll never know if the chips you gave him in that hand helped him to win 1st place but you do know that it didn't help you, lol.
You should definitely take a line that has him beaten if you want to see him fold. AK is not going to make that kind of a shove there (it isn't going to fold either, btw--if that's the kind of hand your opponent has).
The shove is transparent, you're on a draw or a weak pair that his King beats perhaps. Whatever the case it looks like you wanted him to fold and you did, that's not good! Too easy for him to make the right play against you.
You need more information so fire off a large c-bet and make him squirm a little bit, then you'll have a better idea of where you stand. Get him to reluctantly call two streets and when you shove the river he will really think he made a bad decision going any further in this hand. Hopefully for you the
comes out next time and you switch roles, knocking him out and going on to win that precious prize money!