C'mon! Seriously?
I hope this is a gamble in hopes that he looks good and they can find a team to give a 6th round pick for him. It should also make it easier for Tyrod and Cassel to look better as they'll, at least in part, be playing against lesser defenders.
That's one of the scenarios i guess:
1) Showcasing EJ so they can trade him
2) Get a sense of whether EJ is worth cutting or not
3) Keep the colts off balance so they have to gameplan for all 3 QBs in week 1
4) EJ has shown enough to make this a legit 3-man competition
5) Rex is just a weirdo