RustyDios rewrote a script and now you can install this mid campaign and have both the enemy and the autopsy.

Small change to the Voidweaver's AI. It will now no longer run away before performing the summon.
Default boss Action Points set to 1 from 0. After playing with 0 for a while I found it too easy even with minimal mods, you can always go to the ini settings and change it back if 0 works better for you.

Small change in the Imperious' AI. He'll shoot more from a distance instead of always trying to get close for the grab.

Fixed small errors mentioned in the comments. None were critical if you don't want to update.