The thing is, even if he had a bag of weed to ease the meth comedown, weed will be the culprit.
If he had a couple cans of Leo in tow, would they even have mentioned it?
marijuana rarely if ever causes a psychotic break and destructive behavior, and this guy didn't run the wrong way through a roadblock because he was high on pot. There are unexplained circumstances here. The bong is a side issue.