I would immediately question their skill level playing headsup if they offered something like that. If they couldn't finish someone off with so much of a lead then that's a huge red flag. They wouldn't be in that spot if they didn't take risks.
Full tilt used to offer HU SNGs for multiple games and different buy ins just to practice for that situation years ago and I don't know why folks don't advocate for those games anymore.
Folks could practice when they're down when they get a bad beat or work on recognizing
hands to finish off players without playing a really long tourn or a regular hour and a half sng.
I get that its 1 double up =100M, then the 2nd hand/double up equals 200M then 400M so in just 3 all ins, they could be back to almost even with them and the one making the offer HAS to call you at least once to end the tourn. So you jam just 2 more times and you could be back in it. So the stacks aren't that important. And they're still going to have to call you once, lol.
And after the tax man cometh, you're going to be at least giving up 30-35% of that 100k so its really 65k maybe 70k which is still a tremendous amount of money but not really 100k.
I can see where a world level tournament pro that plays a lot of 10k and 25k entry tourns would turn it down because its not a lot of their entries for a shot at 1st place and those folks are trying to build a resume with 1st places for marketing or something.
Average Joe's (who are most of us! lol) playing the lowest buyin of the series like the Colossus and happy with just a min cash, lol, should thank the person giving the offer and ask for a photo to remember the spot and not have any regrets about 2nd place money and thank the
wsop for a great tournament and opportunity.
Especially if they have limited experience playing HU or tournaments in general. I'm sure that's a lot of entries to more tourns and folks can find numerous things to do with that extra money they are being offered for 2nd place instead of wondering later on "what could have happened".