Honestly, I'm not sure what you mean about battleships doing that - they're really slow, so it's hard for them to really disengage, right? The best they could do is back off a bit to hide behind their allies, but that'd just be tactics, and doesn't sound like what you mean. And for example ships like the Onslaught have burn drive, so it's a lot easier for them to go forward than it is to back away afterwards.
The [REDACTED] battleship could get out of dodge pretty easily, but that's a bit of a special case. Some of the battlecruisers are pretty speedy, though - both the Odyssey and the Conquest - so I could see that happening, and now that I think about it, those might be the ships you mean. Still, a halfway fast ship could chase them down, the problem would be doing it safely...
I guess just in general, the AI will back off when it feels like it's in a bad spot. For smaller ships, there are definitely a few cases where it's frustrating, and I'd like to look at those specifically. For larger ships, I think it's - in the grand scheme of things - better for the game for them to do that, as otherwise they'd just suicide into your ships, and that'd be less challenging and ultimately less interesting. And, right, there are a bunch of ways to counter it.