[Suicide Junkie]

When I was playing in my mod, the basse turned out to be much too powerful, and killed off all of the enemies before I could arrive. It didn't attack me after that.

The second time, I'd added more enemies, reduced the weapons and shields on the base. After a long, drawn out battle, the enemy fighters and destroyers were toast, with just cruisers left (who's shields were too tough for the base to pierce).
Hiding behind the base while the two forces duked in out to a stalemate, the mission timer ran out to a success. (The base was still fully functional, as required)
I wasn't attacked by the base then either...