notice he isn't offering a job to work on an android port. He is offering a job to a top developer who is up for the challenge. But since there is no budget allocated to it ("there is not specific android job listing"), then this new top developer will work on iOS for awhile.
If you're hired to port a system to a new platform, it may not be a bad idea to spend time working on it on the current platform(s). Especially since iOS <-> Android conversions aren't always straightforward. If they developed it in Objective-C using Apple's supplied libraries for GUI, network IO, etc, they'll be doing less porting and more rewriting. From then on they'll be maintaining two code bases, not just a fork that replaces certain segments with Android specific patches.
