Yes, I recognized this as a fantasy application of Jim Bell's "Assassination Politics." I think AP would work better in an Iron Age/fantasy setting than in a modern context where anyone with a computer and a 'net connection could donate anonymously to assassination jackpots. In an Iron Age setting, pretty much the only people famous and hated enough to garner significant jackpots would be despotic kings and priests, and their generals. Assassination itself would be as dangerous as the rulers could make it, so it probably would only happen when a king was genuinely tyrannical, or as a substitute for war. In other words, it would take a lot to provide incentive an assassin under those conditions. So, it would probably reduce the number of unjust or trivial assassinations, like a baker "betting" on the death of a rival baker.

In a modern situation where millions of people could easily and anonymously contribute small amounts to an assassination jackpot, it would (in my opinion) be too easy for a million people to, say, contribute a dollar each to a jackpot for some love-to-hate celebrity like Paris Hilton, Bill Gates, or the quarterback of an NFL team that's rival to theirs in the playoffs.

Also, an AP system could just as easily be used by the wealthy and privileged to fund the deaths of any upstart reformers as by any reform movements to target the powerful.