It would be a mistake to hang onto him all season. Of course we're not in the locker room and can't know what is going on behind closed doors but he's doing more harm than good by staying with the team. The Suns have overvalued Markieff throughout this whole process and it's only hurting them in the eyes of fans and I'm sure it hasn't helped their image with other players or other teams management.
According to his brother he wants out and that hasn't changed and nothing that the Suns do will change that. Marcus has taken every chance he's had to publicly bash the team. Given how close the Morris' twins are, what Marcus says about how his brother feels is probably as close to accurate as possible without coming directly from Markieff's own mouth. They should have shipped him out with his brother, either in the same deal or a different one. It wasn't hard to predict they would react negatively to being separated.
Markieff started wearing down his welcome last year with the technicals, trash talking the Suns fans, all followed by his offseason assault arrest. This is the same organization and regime who came in cut Beasley loose, because of his off the court behavior and attitude. They said they weren't going to tolerate players attitudes and antics like that yet they've let Markieff get away with more than Beasley did in his tenure here. They've let Tucker get away with more than Beasley did, with Tuckers DUI and various missed busses and flights. I'm sure other players around the league have noticed the contradiction in how management handled those situations. Add in Markieff's disinterested play this season to kick things off and they couldn't ship him out fast enough, in most fans eyes, yet they did nothing but try and position themselves to trade him for more. Add Markieff throwing the towel at Hornacek and that should have been the final entry in the Morris brothers time with the Suns organization but let him come back to the team after his suspension. They could have told him to stay at home, collect his checks, and wait to be traded but they didn't. Now they're starting him again even though his play hasn't been better than Leuer's, the guy he took the starting spot from.
A team that is trying to develop young players for the future can't have around a guy like Markieff because it only shows that management isn't to be taken seriously. The team has Len, Warren, Booker, and Goodwin, even Leuer possibly, to think about in regards to the future. Letting one player, who wouldn't be starting with most teams in the league based on performance alone, get away with disrespecting the coach, management, and fans surely doesn't help build a positive view of the franchise.