I think you’re nit picking the idea, inventing flaws and strawmanning them. No one ever suggested those things you’re saying.
The whole point is relying on the moderation to handle itself. Not babysitting their actions.
They could hire new people to do that or subdivide duties from people who already work for them. That’s how a company works, you don’t always need to hire new people for everything.
They can also interview trusted people and make it a “voluntary” job. Although a less stable option I’d say it would mean less work for DECA in the long run and they should be able to undo actions based on a log so no harm can really be achieved by a voluntary (worst case scenario, extremely unlikely but can happen).
What (of the several ways this could be implemented) path they choose is up to DECA but these are just ideas. No one really knows how much they make, if they can/want to hire new people or invest in this system. But it’s probably one possible solution nonetheless.