Possible reasons why iOS first
Someone said "Why iOS before Android?" I'm not linked to Zeebox but I can suggest some possible reasons.
1) Zeebox started with the iPad (rather than iPhone) and if you are primarily targeting tablets iOS is the obvious option based on numbers and the reasons below.
2) Even if sold numbers of Android beat iOS they may not be used quite as heavily so in usage time (ad showing opportunities) iOS may be bigger proportion than in device count.
3) All[significant exaggeration] the media have iPhone/iPads so more likely to get press/news coverage etc. Also this applies to potential investors.
4) Fewer device variants to worry about in terms of testing on iOS than Android means quicker release.
There are probably more good and bad reasons but it would seem to me to be a reasonable choice to develop on the simpler (in terms of devices to handle) platform until the app is refined and operating at a good level with reputation built before making an equally good app for the other platform and introducing it when there is already demand for it and you can commit more time to testing on a variety of devices and software version.
More "Elementary Dear Watson" than "No shit, sherlock" but I thought I would use Mr Homes' icon anyway.