This seems to be a common rationalization from prosecutors and police. What they fail to realize is that falsely imprisoning even a 'bad guy' undermines the whole system. It has led us to the point where no one should ever speak to the police. A cycle that makes it even harder for police do properly do their job.
There may be a bit more to this case: "Scott said he had gotten the gun, a Tec-9 semi-automatic, from Dixon and the two men had driven together to the crowded corner where the fighting broke out." (http://www.espn.com/golf/story/_/id/24736866/valentino-dixon...)
This type of statement is highly infuriating. This has no bearing on the fact that the original prosecution withheld evidence and he was not the shooter in this case.
He was an accomplice to the murder, having supplied the illegal murder weapon - a TEC-9 semi-automatic pistol - and having arrived at the area of the crime in the same vehicle.
So yes he was in fact a bad guy and yes he did deserve to be in jail for aiding the crime - he shouldn't have been convicted as the shooter and his prison sentence should not have been nearly so long as it was.
"He's a bad guy, so he deserved to be in jail anyway".