Special Forces attacking human controlled planets?

[Minotaar]

So I just fired up a new game and attacked a planet with a CSG-E. The special forces start trickling in. I fight them for a while, then pop the command station, they pull back out. I build my own station and  leave the CSG alive as I need it for my evil schemes. Everything's great.
Until I order my fleet to leave for the homeworld, at which point 13 ships immediately enter, one-shot the command station under a bubble (yay Blade Spawners) and run away again.
Threat counter shows 1.
Bastards.
WTH?
1) intended?
2) emergent retribution for cheesing?
3) bug?
I'll try and produce a save if necessary.

[Fluffiest]

Pretty sure that's unintended-but-desirable emergent behaviour. The Special Forces respond to the distress call from the CSG planet, but once they've set off they don't keep checking that the AI command centre is still alive. If you leave the planet neutral for a bit, they should show up, get bored, and wander off again.

[keith.lamothe]

If they still had a wormhole path to that planet they may still complete it.  Sometimes they won't.  Overall I'll just call this example an "extended defensive action"