I'm pretty sure Athos' page says he gets magic in base form, before transformations - so even if Flight is a magic spell, he wouldn't be flying at jet speeds.
But really, How good is Athos' Durability - Do you believe he can survive a Psionic Storm? Numbers already said earlier the thing rips up battleships - I don't call his odds good in this situation.
The only person on the field who can do a thing to Fortune is.. Cielo. And thats by literally ramming into her. If Cielo is stunned for even a -moment- by Kerrigans initial Psionic Storm, Grabner can pick up the pieces and rip him to shreds.