A private organization putting together an event to expose girls to careers in STEM or aviation, and an airline supporting it by putting together an all female crew, does not deprive any male of any opportunities he would have had otherwise.
So if it had been for boys only would you say the girls had not been deprived of any opportunity?
If gender discrimination is wrong we should stop doing it.
Period.
Rationalizing that new injustices are necessary because of prior injustices is baloney. Those who choose to discriminate always seem to have some "greater good" excuse.