Why not iOS? Because Apple doesn't allow emulators.
That's my guess. Given that Amiga, Inc. doesn't have a lot of technical know-how, but does have a willingness to, erm....how to say this...I don't know they seem to specialize in brashness and losing legal battles.
So - what makes the most sense to me - and this is purely speculation, is that someone wrote an Amiga emulator, Amiga, Inc. got ahold of someones work in that area... Amiga, Inc. is packaging up the original binaries, hiding the emulation - and you know enough hooks to use the touch screen for control.
To the user, its a faithful reproduction of the original game...all guesswork, but with Amiga, Inc. you don't necessarily just guess they got a license and had the knowledge to do a port
If anything, that's an even crazier guess.