The situation is simple. With Mithridate's

penalty for an unimportant move you need to find another player for Sicily. The faction is basically destroyed. Replacing the buildings and removing only the small amount of money I received was enough. The only advantage I received was that Sogesu had a very unhappy population since he obviously only settled in the city. He did not exterminate or sack Iraklion or Rhodes so the the money he received would have been minimal.
If saying that he could reach them in a couple of turns (which Mithridate does)was valid excuse to prevent destroying buildings then sorry every city on the map is capturable using this logic and thus no one, anywhere, can destroy buildings in his regions.