The UN isn’t “stuck” with anything. If you haven’t got anything worth sending, then don’t send it.

An interesting idea. It would cause a stir. First of all, the security council (in voting for an operation) would have to give the executive the power to reject troop contributions.

One problem would be this: If the UN rejected offers of troops from any country which had ever sent somebody who’d been suspected of child molesting while on duty … there might not be any countries left to send troops.