JV my fans blow on the walls and the ventilation bounces back to the plants so it is a very gentle breeze in there. As for blowing off the ethylene, I suppose it is possible.
Part of me thinks the ethylene is pretty pervasive as I only used bananas on two plants out of 4 on the table and all 4 were female. I know I'd never put a banana of my e&f table if I wanted a male.
BTW, you don't want to keep a banana so long you get fruit flies! Toss it and put another one down.