They're setting up for their attack, but decide at the last minute that they don't have enough forces.
yeah, but then they just keep thinking oh, i want to attack! wait, no i dont. oh, i want to attack! wait, no i dont... its like a person with 15 second short term memory loss (50 First Dates?)
i mean... how does the AI know you have a fleet around your planet? unless it has the Advent Culture side effect (which in this case it didnt), and Advent planet monitoring ability (the one their capital ship has, i forget the name) a TEC probe ability, a phased out Vasari Scout in the same GW, or some other way of gathering intelligence, the AI shouldnt be able to know where all of our ships are. maybe on unfair you can cut corners a bit, but for normal etc, it shouldnt be like this.
and in the end, what good is the AI if he just sits there trying to jump, deciding not to, forgetting why he decided not to and trying to jump again? i relaise its hard to program AI with intelligence, but maybe a line of code that tells it to jump to another planet, or launch a super weapon, or something like that. but 15 second memory loss is BORING