I believe that this situation, as well as the AA all-in at first hand of Main Event, is not trivial. Well, they are trivial in theory. AA is snap-call. We study and train for situation like this. We want to be able to take the best decisions mathematically. That's why we follow bankroll management too. But these two questions have one thing in common:
they are not everyday situations. This one, being in a Heads-up for a 6-digit score, does not happen everyday, specially in such a large event.
With this in mind, I would build my answer following these premises:
1. Theory point of view: being a 12:1 underdog in chips, his proposal is like a gift from heaven. I love heads-up, but everytime I play it, even against a weak opponent, the chances of losing are quite high. HU is a game of high variance, people might get there much more often because of the large ranges. With 5 BB, I have to go all-in with so many marginal hands, and the opponent will call us with many marginal hands as well, and he still would have a lot of
equity. Also, with his chip advantage he can wait a little bit. He does not need to call me with K5o, for example, or even a Q6s. He can perfectly wait for an Ax or better King, knowing I would push my 5 BB very very often.
2. Emotional point of view: getting a bracelet and the glory of being a WSOP champion is amazing, but it can not (or should not) make me take emotional decisions. So many times I would lose my 5 BB and consequently, the bracelet and the extra money he offered to split.
3. Financial point of view: it does not matter if I don't have much money, or if I am very rich, this also should not be a factor to make me decide based on my current situation, like: "I don't need money, I want to gamble the bracelet"; or like: "I really need it, ok, take it and thank you". No, this needs to be evaluated mathematically.
And math says that my chances are not that great, even if I was Doug Polk himself!
Therefore, my answer would be: "Thank you, mister/miss, I really appreciate it. You can take your bracelet, you deserved up to now, and I accept your proposal, it is very kind of you. Congratulations!" We shake hands and I register for the next event happy with a good, sound and rational decision