I think the issue here is (sim) PBEM games. I know there are Posts from other players here having the same problem. I have been able self-destruct in Turn-based games.
I just did another install of 1.41 and will test with the most current.
You're right there, all my experiance is with single player/hotseat.
If you can't find a solution maybe you can give them to an ally (or enemy) if you promise to sweep them. Then you could backstab them and keep them from launching more units!