If I had to guess (and it is a guess) they knew they were doing an Android tablet form reader and waited for some of the development until they could be assured that they were, to the greatest degree possible, developing something that would (mostly) work for both the Vox and other Android platforms. Android tablets are catching on now, but remember that iPADs became popular quite awhile before that. Android also was releasing new flavours of Android that would be better on tablets, and that has only happened fairly recently.
Most of the Android apps are on phones, at the moment.
Taming Goes Rogue