Of course it's shit writing:
-Sanji can outrun them, break the roof and fly away
-Somehow he escaped her web the first time yet somehow he's supposed to be caught here? Why can't he escape again?
of course this will be unexplained because of the offscreen
It's the same writing that let Toko, a 8yr child outrun Zolo and Brook right to Yasuie's execution in flower capital (that's a lot of distance):
or
Hiyori outran Killer while carrying Toko
Oda is a horrible writer, he can't come up with anything new.
You can see from his arc structures, they never change.
He has no imagination as to how not let Sanji to the roof
while also not letting him encounter calamity too soon (because he always gets his fight last out of everyone)
or not just beating everyone up, because that would make the raid too easy in the dome