If Turkoglu was 20-years-old, this mistake would have been understandable. Young, inexperienced people are going to do things without thinking about how it impacts on their boss. Lots of people leave work early, take a rest and feel better. But they usually know not to show up somewhere later that is going to make it look like they were not really all that sick.
Turkoglu backed Triano and Colangelo into a corner where they had to respond. No matter what his agent told him the team's response would be, the only course of action left for him at that point was to apologize for embarrassing his coach and live with whatever punishment was dealt out. Turkoglu's actions could not become the standard accepted by the Raptors coaching staff.
All of what happened with Turkoglu in 2009-10 should be fixable and at least some of it can be blamed on the Raptors organization for failing to treat Turkoglu the same as any other player and over promising what they were prepared to do for him on the court.
Turkoglu is not the first player to underperform after signing a big free agent deal, to have issues with how he is being used, to make some bad decisions, and complain to the press while suggesting he does not want to return. It would take some serious effort from both Colangelo and Turkoglu, but Turkoglu could be back with the Raptors next season.
The question will be does either of them want to make the effort? At this point, it does not appear so, but things could cool off over the summer.