When a team gets on a rooftop it creates many potential problems. But the game mechanics allow for this to be done. If it is such a problem then ladders should be removed altogether, I dont really care.
But since ladders are here for now, and rooftops are accessible when using them, this is how I deal with the ladders.
If the roof top people break their ladder after going up, then I am going to kick them if they dont get down. If the other team breaks the ladder to force them down, I am going to kick them. I think both actions are cowardly. If delaying comes into the scenario then a different action might be taken.
There is only so much you can do about it. It could cause delaying, it could cause an unfair advantage to the people on the ground, it could create an inaccessible location, etc. People will cry foul on the ground or the roof, attacking or defending.
So if you see a ladder placed to gain rooftop access, leave it alone. It is the only option that is fair to both teams as long as ladders and rooftops are in play.
In this specific incident, the roof top people had a disadvantage. They were outnumbered and there was plenty of time left on the clock. They did not break their own ladder, leaving the other team access to the roof.