As long as they can collectively outfight the Hypothetical Corrupted Governance Military, yes.
This is easy while everyone's a farmer. The police outfight individual thieves, the collective farmers win against the police.
If all this social complexity enables you to build more powerful weapons, and the police have those weapons, and nobody else has those weapons, then there is perhaps a bit of a problem.
Civilization spends around a third as much as making sure Civilization can collectively outfight the Hypothetical Corrupted Governance Military as Civilization spends on its actual military, and even then there's some real and awful questions about whether, for example, the military plus the Keepers could take the rest of Civilization. There's an order of Meta-Keepers whose job is specifically just 'keep an eye on the Keepers', and in real life that's probably worth anything. The Keepers hopefully can't win against all the rest of Civilization plus its usual military; and the usual military is in fact specifically designed to resist Hypothetical Corrupted Keepers. One similarly tries to make it hard for the Keepers collectively and the Military collectively to trust each other in a pact to take over together, especially when they were already betraying their oaths to Civilization.
It's hard to have a really simple reason why Governance couldn't possibly go corrupt, once your weaponry reaches the level of 'giant flaming craters'. Civilization has thrown complicated solutions at this because they don't have simple solutions, and nobody is happy about that. But it's not like 'just don't build overly powerful weapons' is an answer, because how do you stop rogue groups from building those, possibly in secret, if there's such a prize to be won by being the only group with overly powerful weapons?