No one is making any noise that the autopsy showed the innocent little waif had Marijuana in his system.
The reason no one is making any noise that the autopsy shows Marijunana in his system is because it is irrelevent to the case.
There are plenty of drugs that make people aggressive and likely to instigate a fight - drugs like PCP, meth, etc. - but cannabis is not one of them.
Also cannabis stays in the system long after it has stopped effecting the user (up to 30 days). So it is possible that Travyon could have smoked pot a week or two prior to all of this, and it would have absolutely no bearing on the trial.
All that being said - you are responsible for your own actions. If you are drunk and you go start a fight, you are responsible for what happens to you - it’s YOUR fault, not the beer’s fault.