This thread has gone far afield, and some of the discussion is admittedly entertaining, possibly even interesting at times.
But, let's keep a focus on the original question that was asked. The original question had nothing to do with smoking marijuana (or eating it), for example. The OP was expressing an opinion about a dive shop using a picture on the shop FB page of divers smoking, and asking for the reaction of others.
I tend to agree with the OP - speaking from a US perspective, as a dive professional, I think it is foolishness and bad business to give an indication of condoning smoking and diving. If I was a shop owner, and an employee had the lack of common sense to post such pictures, I would possibly suggest that the employee consider alternate employment venues. In another culture, where smoking is still prevalent, that might not be true. But, as the negative primary and secondary effects of cigarette smoking have become more widely known, as has the addiction potential, it is hard to understand why people start. (And, I confess - I say that as someone who enjoys a cigar several times a year.)
I don't see the OP's comment in any way as a slam at the scuba industry, and I can understand the vigorous annoyance with the picture. Suggesting that an employee who posted such a picture in this day and age could be considered a brainless idiot really isn't name calling - no employee (or even the dive center) was named - it was so impersonal and detached, it hardly constituted a personal attack.
So, if you disagree with the OP, and don't think it is unwise from a business perspective to post such a picture, say so (and several posters have). That kind of feedback is what was being requested. Personally, I think is is. I use to tell one of my daughters, who seemed at one time to be unnecessarily fond of posting candid thoughts on Facebook about some of her restaurant co-workers - usually after a particularly busy night at work - that she should not do that, because her employer might well see those posts on FB. Yes, it was her personal FB page, but - as I told her - in the past I have decided against hiring people at times because of their behavior on their personal FB page.
Business owners - FB is not some detached, independent media platform that has no influence on business. Even your personal / individual FB page can reflect (positively or negatively) on your business. Something to think about.