The Colts seemingly are incredibly interested in Robert Griffin III in the upcoming draft or are at least doing their best to convince us they're interested.
Nate Dunlevy tackles this possibility with his usual deft touch:
Sorry, not buying it. If they were making a late-in-the-game push to go after Luck then that means they didn't have enough information back in March to cut Peyton Manning.
You could really quit reading there because he's absolutely right. You'd miss Nate debunking other theories so make sure you read it anyway.
Still the point remains that the Colts essentially released Peyton Manning and said they'd draft a quarterback. You can't convince me they had any doubts regarding Andrew Luck at that point. Robert Griffin was not likely part of that consideration given what we knew at the time.