I still to this day cannot understand how Spacebattles believe being able to fly by itself means anything in a battle...
If you are able to fly like Superman and fly far faster than your opponent, then it wouldn't matter either way. if you can fly at the same speed your opponent can react to, it's not much of a boost because while yes, you can move on 3D, that's not much of a boon because of the fact that the opponent can and will meet you head on.
And if you specialize in long range attacks and they don't, flying doesn't give you a huge edge there either because your long range attacks would still be huge because you are far away and they need to be close to attack you.
The problem here is that nothing I see here from Fern would suddenly mean it's a danger to Gaara, especially in the field where he fought Kimimaro at because that's where he can create whole ass sandstorms even then, making the advantage null and void.