Mitchell has every right to be pissy in this situation. There are two options here and none reflect great on the organization:
1. Mitchell's injury is worse than we're being told, which if that's the case, it's really ****ing odd that they took him off the injury list and basically led the team, media and fans to believe he was going to play, just to abruptly change course. If they are that concerned with his injury, it's really hard to rationalize that two days will really be the difference maker for his needed return after he sat out the last six weeks. And that still doesn't get into why they moved forward and acted like he was playing. If Mitchell, and the coaching staff, as well as the team, thought he was playing, that's just horrible transparency and communication from the trainers and Mitchell deserves to be angry.
2. Mitchell is ready to play, but the trainers forced him to sit out of ****ing spite.
Those are the likely two options we're dealing with here and neither make Utah look good.
Your trying to pin this on Mitchell is just wrong. Mitchell should be raising hell, especially if it's the latter and he was only sat due to some weird power struggle.