The shield gens are supposed to all count when they go down. Vengeful is a hard AI, and it should respond pretty energetically when you remove one of its key defenses.
That said, since it was putting out a "red-hard" performance there, for 7.034:
* The Vengeful AI's response-exos when you blow up something it cares about has been halved.
** The response for destroying non-A core shield generators has been further halved, as the chain reaction of all of them going at once can be quite... energetic.
The vengeful's numbers have been like that for over a year so I'm not going to do a hotfix just for that, but it should be out this week.
Anyway, thanks for the report and the clarification, I was rather confused about what could have spawned such an attack with no warning. Answer: somebody put in the emotion chip.