)
The issue I take with the way the villains were handled is, well, the way they were handled. Discord made it very clear that being a statue was a horrible experience, and one can see why! Being fully conscious, yet unable to move, speak, or talk, stuck in one place for an indeterminate amount of time. Sending them to the moon would’ve been more humane, but most humane of all would be Tartarus, which is a prison.
No one, no matter how evil, deserves to have their basic rights and dignities taken away. Especially not out of petty vengeance.
Edit: Discord being the source of said petty vengeance, he suggested the statue thing knowing full well how awful it was, and he picked it to “get back” at the villains for betraying him.