Just fought a battle against 2 heroes and some defensive stations as the Imperial Remnant; I deliberately avoided targeting the heroes so they could retreat and I'd get them when I integrated the faction. Even though I massively outgunned & outnumbered them (2 star destroyers on their end vs. 4 on mine, an allegiance, & enough support ships to fill the pop cap), they didn't try to run. Neither had any traits that disabled tactical retreat, and I didn't have any interdictors on the field. They just kept attacking; I sent my fleet to a corner of the map, had my bombers destroy all their weapons (but not their engines), and they just followed my fleet to their corner and suicided, even though they could have just run away. I cannot possibly imagine why the AI would do this.