Your right, its not perfect, but remember the Imps are still second player and should be getting the advantage. The way you have it worded takes all strategic choice out of the objective, essentially guarenteeing for the Rebel player that if they now just turtle at their goal line the entire Imperial fleet must come at them like lambs to the slaughter.
That, imo, is worse.
There is a balance that has to be struck between theme and open ended playability. If the Rebel player turtles, i can hit the brakes and deny. If Imperials turtles the Rebels know they just have to scratch something to get an easy 40 or 60.
But 9 times out of 10, because there isnt a much incentive for either side to turtle, the objective will be played like peoplr want it to be played- with the Imperial player trying to finish the game with at least 1 o 2 of his ships in the deployment zone.