Besides which bug bounties are not really intended to disincentivize people from committing crimes, they're intended to incentivize researchers to report findings and reward them for their efforts.
Doesn't matter for our case, since it already assumes the database potentially compromisable. The parent's comment concerned whether the "bounty for capturing a flag inside a publicly available encrypted vault" is enough. So the question is not whether the bounty is enough given it's impossible to win, but whether it's enough given it might be possible to win.
In other words, whether someone who finds an exploit to decrypt the vaults contents would get a better value by (a) revealing it to 1Password company and taking the $100K bounty, or (b) selling the exploit to people who would give millions to be able to decrypt other's vaults...