Problem is that while pilots can get iPAD specifally for the flying, they usually already has a phone, and it is Android in 50%+ cases.
And actually Garmin Pilot benefited a lot from this gap in Android market, as it is the only FULL (I tried few others and no one is full) aviation application for android. It is not so mature as FF (or even as GP for Android) yet, but their android version has all features except maybe terrain, and they benefit on IPAD-s from having Android too (as I can have GP on android phone and on iPAD tablet for example, for the single subscription).
Problem was that Android tablets was actually very bad and unreliable until maybe 1/2 year back, but modern ones (Samsung for example) are excellent and technically are better then iPAD-s. So this is a very fast growing market. if FF choose don't work on it, they will lost part of iPAD market as well (because of need to have the same subscription on the phone and tablet).
(I posted my experience with G.P. on Samsung tablet in G.P. specific thread - very positive experience, I should say.)