Ex Crossup for air finish is gimmicky and reason it wont work is, usually people will end the combo with air throw, 2ndly, if you did EX crossup the flash itself would give them enough time to already think of what to do, so they can time a tech and just let the whole attack whiff, 2ndly, you then will have to wait till you land to recover from the EX cross bow, its not like you gain a free jump after you did EX cross bow, ur in crossbow recovery animation for the whole duration till you land. and there is always the option of shielding