Realistically, the only thing that results in a "how their rulers should be held accountable for it" is a violent change of regime. There universally are large groups of local people who'd like their corrupt rulers to be accountable, so you theoretically could support that process by buying and delivering large quantities of weapons to the opposition of the regime so that they can (try to) overthrow it and bring justice to the ruling clique. Or, alternatively, orchestrate an external invasion either by neighboring countries or USA.

However, is this really what Bill Gates should be trying to implement in other countries?