Persistent cannabis users show neuropsychological decline
pnas.org
pnas.org
So this is like the beef council funding a study saying 'BEEF IS AWESOME FOR YOU AND MAKES YOU SMART AND HANDSOME.'
Move along, nothing to see here (until you see the results replicated by a less overtly biased source).
Second, more seriously, your response is political rather than scientific. There may indeed be flaws in the research, but so far you haven't indentified any.