Some speculate he wants more money from the Cowboys, but I don't see that one being likely.
I see two different scenarios he could be thinking, he really wants to retire and don't want to pay back bonus money, or he wants an opportunity to start somewhere.
If he really does want to retire, he holds a better hand than the Cowboys. It'll probably be a stalemate with fines up until the start of the regular season. Once the season starts, all he has to do is return to the team, and chances are unless we are really desperate to retain his services, that will force the team to cut him. Until then, there is no reason for the Cowboys to do so. One roster spot on a 90 man roster with several guys being no more than just bodies that are not expected to be on the 53, one more won't really hurt. Once training camp starts, they can put him on reserved/did not report and get that roster spot back. If he don't report, he doesn't make any money this year, but he doesn't have to pay back his bonus money. If he shows up just in time to start the season, its unlikely the team would allow him to keep his job as the backup QB, and he's not the kind of player you want as your 3rd QB. Plus his salary for the year would be guaranteed if he is on the active roster the first week of the season, so that's when you cut him.
If he wants to play somewhere else, then the team holds the cards. They can hang on to him until he decides to report, and then cut him, or choose to hang on to him til cut down to 53. At that point, no team is going to be interested in giving him a chance to start without having any practice with the team.
The bottom line is, the Cowboys should force him to play his hand before they do anything, and unless he decides to show up for camp in good shape, with a good attitude, and competes and wins the number 2 spot he's played his last snap as a Cowboy. Whatever the Cowboys do, don't let Orton win with a bluff and get a chance to go somewhere else this season by cutting him before its necessary.