There's always the ability to impose more lenient terms. Hell, at the extreme end of things we could all just forgive every mistake and never impose terms. But if MK wants to discourage people from spying on them, there has to be a severe enough consequence. That means halting their growth, destroying some infrastructure, teaching them a lesson. They could have crushed UBD to dust, or they could have just let them off with a slap on the wrist, but they didn't. This is the lenient side of middle ground.