Just because a building is occupied does not make it inherently safe if it is on fire. The same is true for vacant buildings; just because it is vacant does not make inherently dangerous just because it is vacant. It also doesn’t mean it isn’t occupied.
Operating on the roof during a building fire requires us to have a secondary means of escape. This will likely be the responsibility of crews on the ground. But, if resources are such, the vent team may need to place both sets of ladders prior to making the roof.