If you're only allowed to disengage from a dogfight you survived last turn, not from a dogfight which has been declared this turn, then it should not be too powerful.
Using the same example again, Razik dogfights Sky Serpent and Star Snake at once. (What probably happened was that the Centauri got to move first, the Razik jumped the Sky Serpent, then the Star Snake jumped the Razik. If the Drazi had moved first then the Star Snake would have jumped the Razik, which being now stuck in a dogfight, could not go after the Sky Serpent.) Razik attacks Sky Serpent, Star Snake assists; then Star Snake attacks Razik, Sky Serpent assists. Dice are rigged so both attacks are draws. Next turn the Drazi get to move first; Sky Serpent disengages, Star Snake continues to dogfight Razik, so Razik can't get a free shot and can't chase the Sky Serpent.
Re-run the scenario but this time the Razik draws when it attacks the Sky Serpent, then wins when attacked by the Star Snake. Next turn the Drazi get to move first; Sky Serpent disengages, Razik gets a free shot, then can chase after and dogfight the Sky Serpent again.