I've been excited for this for a long time.
One of the things that has to be realised was that when FEZ was first signed with XBLA, it was the only place for indie games. FEZ was in development for over half a decade, the scene can change a lot in the time a contract cannot.
Ultimately, Fish was failed heavily by Microsoft. There was a severe bug with one of the patches which was a very easy fix (and due to the nature was not picked up by internal testing,) which would have cost him ~$40k to fix due to Microsoft's incredibly limiting patch verification process. For a two man indie job, this was pretty much out of the question. If I recall correctly, you get one free patch with the contract (Which also costs - just to get on the system), then you have to pay.
In the time he was developing, steam started rising. The Humble Bundle came around, and the entire landscape for indies changed. Steam was offering no contracts, free to get on the store following approval, and an unlimited, free, and instant patching service. Unfortunately, he was tied in to MS for a year.
Since he made those comments, and since he first signed FEZ, the landscape has changed dramatically. He's being honest about porting FEZ purely for the money, but it's his baby. Anyone in their right mind would want it on steam. I know for a fact that he has talked a lot to team meat, and they are the definition of a huge steam game that petered out hard on XBLA. They sold an order of magnitude more on steam in comparison to XBLA, and constantly sing it's praises.
This is an interesting read from Giant Bomb;
http://www.giantbomb.com/articles/the-rabbit-hole-that-is-life-after-fez/1100-4275/
And this is the interview I watched that has a lot of the information and his perspective on things after the release of the game;
http://www.youtube.com/watch?v=0LG1fOOUSOw EDIT:
In the above video, the part about working with Microsoft is at 10:40
The part about the patch is at 13:10
The part about Steam is at 15:25
The part about porting is at 22:00, More specifically 22:47. This is what I meant - He's passionate about his baby and he wants people to play it.