Telling people they need to STFU is a far different message than what you wrote.I think maybe you misunderstood what beester was trying to say.
He was referring to newly minted GUE fundies divers as being more likely to give GUE a bad name by being too critical of others and having a less nuanced perspective, making it seem more cult-y.
In other words, the reason why you talk about GUE being a cult, is probably because of some inexperienced loud mouth divers who took a GUE class and think they know it all, when actually the experienced GUE divers/instructors and the general community is anything but a cult.
Yes, they have a zero tolerance for smoking. Call it exclusionist if you want. They're not trying to be for everyone. I understand the reasoning for not wanting to associate with divers that willingly harm their lungs and put themselves at unnecessary risk. Especially considering the goal of GUE to be at the forefront of exploration with pretty aggressive diving - it makes sense to focus on minimizing risk.
The former will more likely result in a reaction of GFY. The latter more likely give a person pause.
This reminds me of those skits of translating rude responses into something business appropriate to put in email.