yes the airflow i always keep closed when im putting it back together after cleaning etc, followed advice from a long time vaper. They claimed the flooding was because i was reassembling with the air flow holes open..
Well, all I can say is "in the old days" trying to tighten up anything without somewhere for the air to go was a guaranteed flood. Carto tanks etc, all needed a filling system that stopped the juice rushing into the atomizer as the pressure builds. SO, logic tells me, that as a BVC is actually very similar to a carto-tank, unless you keep the airflow open, it will flood.
OR, put another way, I have only had flooding when I have filled it with the air-hole accidentally closed. So my suggestion goes completely against your friend. Try for yourself, but don't rule what I am saying out.

The choice is yours.