Author obviously has a conflict of interest. He fails to acknowledge that correlation is not causation and that these studies fail to take into account other variables that could influence the outcomes.
I don’t think you’re using conflict of interest correctly. You’re saying here the author has secondary motives, such as being sponsored by an anti-weed org or something, which they would have to disclose in their own section (as per basic academic standards).
You might want to instead if you want to criticize the research say the authors clearly have a personal agenda or bias.
I don't think they have any shortage of patients in rehab. There is already a steady stream of them. Rehab counselors are often former addicts just trying to help others live through what they did. It is not exactly a way to get rich.
I read the article and did not see anything that would qualify as a conflict. Correlation is not causation only on its face, which is why researchers compare their findings against control groups.
You might want to instead if you want to criticize the research say the authors clearly have a personal agenda or bias.