I am not going to say “the customer” since these forums are obviously free of charge. But who is the targeted consumer? And how is this consumer best served? I think this consideration should help guide the policy of the moderators.
I think the impersonal approach where moderators simply enforce the letter of generic forum rules makes the most sense if we are talking about some sort of unattached general forum. But seeing thus forum is adjecent to the website of the LvM Institute which has its own mission, this is not necessarily the best approach.
Now I can accept the moderating policy as is if it is felt that this is the way in which the targeted consumer is in the long term best served. (Eg if there are fears of a “slippery slope”.) But if this policy has as an effect that those who are a part of the targeted population are less likely to participate on and benefit from the forum then the policy can be counter-productive.
In that case I would call for moderators to use greater personal discretion in order to in some way restrict the participation of posters who are not among the targeted population when and if their posting in some way drives away a portion of the population which is being targeted.
Of course this would be a form of discrimination, but as libertarians we have no problem with discrimination on the part of private acters, it is only the states as non-owners of property who have no right to discriminate.
Or to be less-generic, I am asking the question is having posters around who are not teachable worthwile if their presence makes some of teachable posters less likely to participate?