Yes. His opinion is probably "managers make worse decisions while high" => "Weed is bad for business." Which is not the same as "The weed business is bad."
As a die-hard fan of recreational marijuana use I can tell you from personal experience that you really should be sober at work. Not only does drug use at work destroy your productivity, it also blurs the distinction between work and pleasure. While this might seem to “enhance” your working experience at first, it also devaluates your spare time and precipitates burn-out syndrome. That knowledge might be trivial for most people, but this seems a good place to spell it out.