Like I said, I was not playing, but if you dropped some bombs over the bridge and killed players on the other side of the bride, then you were attacking the last flag.
Dont forget the reason of the no air attack on last flag rule.
The reason is to avoid the base rape and make the game more enjoyable.
If you are too greedy and like to base rape and you continue dropping bombs you will make mistakes like you did, and you will be kicked/banned.
You have some choices in a last flag situation.
Continue flying and wait for vehicles/enemies trying to escape to other bases to attack them, or, bail from jet or chopper and help your team on ground to cap the last flag.