The 20k and the 5k decisions were completely different scenarios.
The 20k was for just one person to the exclusion of others and represented a large share of the prize fund, plus someone had to be evicted. And I still don't think Jason did anything wrong pressing that button, given his circumstance.
The 5k was on offer to everyone, and everyone could have taken a fair share. I have no doubt neither Alex nor Jackson would have taken the money if they knew it was just two people. Jackson got confirmation there was no catch or consequence to the decision. It was 5k, no catch and everyone could take their share. Given that decision as presented, I'd question anyone other than Jason who didn't choose rich.