Looks to me like he has a strong King judging by the call and then the big all-in is designed to look like a bluff. After all if he has an Ace then why risk most of his stack when you could easily have a King ?
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I’d also consider the following…….
You have to assume that he has some ability to get this far in the tournament and therefore is not making a stupid play.
The fact that he’s only just arrived at your table means that whilst you don’t know his style of play neither does he know yours.
He is not under immediate pressure to make a big move.
AKK is not really a great flop for A10.
20k chips is not dramatically worse than 23k
My tournament life is on the line here and the money’s not far away.

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Having considered all these points it’s a fold for me.
It’s not clearcut by any means though, which is backed up by the varied replies so far, as you could be ahead. However, for me, there is too much risk to justify the call.