He is doing this simply because Iowa went red in 2004.
Here's hoping the state legislature voids his executive order.
He did this because he has aspirations which require that he make friends in the party at the national level. I'm sure they're all impressed by his timing. The felons will get to vote in the upcoming November gubernatorial election before the legislature reconvenes in January. Meanwhile, it can't hurt him, since he's not running.
Admittedly, it's a brilliant move on his part, and it looks like the SOB may very well get the last laugh.