I think it's a bit more nuanced then that. If you dig into this case a bit it seems pretty likely that this Scott guy "worked" for Dixon in some capacity and even if Dixon didn't pull the trigger he provided the weapon and was at the scene of the crime when it happened. I think the most likely explanation is that this killing was directly related to him being a drug dealer and him having one of his gang members kill someone else. Like doesn't it seem a bit odd that this other guy was so willing to take the fall? Sounds like a lackey trying to protect his boss.

Just saying, I don't think that was just an excuse. I think they had good reason to believe this guy was a bit of a low level crime boss/gang leader and they decided it'd be better to put him away even if he didn't technically pull the trigger. Yea it's an abuse of the justice system in a lot of ways and I don't condone it, but I don't think it's as easy as saying the DA just wanted to randomly pin the murder on someone else.