AFAIK the airspace on an apartment lot balcony is the same as the airspace inside an apartment lot.
I’m not 100 per cent sure about this, but Vic law and NSW law differ on so many things I wouldn’t take it for granted. In any case the strata manager’s “air space” argument is spurious since section 153 of the act refers to nuisance from inside units too, and NSW strata law allows owners to regulate what people do on their balconies through by-laws