Obvious to you but it seems not obvious to them. And i bet they know more about business than you, no offense.It seems obvious to me that if they want to cut their losses, they'd make more money with a PC version than without after the cost of developing a PC version.
Consider this: they put millions of $ in the development of the game, paying 2 or 3 developer (i don't even remember how many teams worked on I Am Alive, but more than 1 anyway).
Why should they put another 100k or so into a PC version that might not even make that 100K (not the original development money; just the PC port money) back?
For a niche-genre game with 0 hype every version would sell poorly, regardless of platform. So after losing millions, you'd be willing to lose more just because you know for a fact that the pc version would sell what, 5-10K more copies than the XBLA version?
You'd make a terrible business man and you'd probably bankrupt a game-company