When it comes to entertainment I'm hardliner: I don't really care if people are playing serial killers or child molesters, as long as they're just saying it (or even drawing it). I might raise an eyebrow at the ickyness, and say that this is not something I'm interested in, but whatever.
I partly agree, partly disagree. On the one hand fantasy and art are not reality, and don't have the same moral weight. On the other, what somebody chooses to fantasize about doing, in at least a semi-personally-identifying vicarious way, for his own enjoyment
can raise valid warning flags, and there are subjects and courses of fantasized action which invite more such flags than others.
I think it's valid to say that objecting to a player who wants to spend game time on enslaving NPCs and slave-trading, or to a game which encouraged such choices as an expected and prominent course of action for PCs, goes beyond personal ickyness. However, I reject TBP's approach because it's clear they consider even raising such topics to be tantamount to endorsing them, and are reading any reported complaint assuming the worst possible bad faith on the part of whoever is complained about.
I don't think I have ever heard of a murder spree being inspired by the music of Cannibal Corpse. In fact, I think the general effect is the opposite; entertainment and "blowing off steam" tends to lower our tendency towards violence, and I do have some general observations over time that supports this.
Again, I agree and disagree. For most people fantasy can be a valid and safe way to exorcise antisocial impulses, but there
are people for which certain fantasies only serve as fuel for the boiler pressure within rather than as a relief valve -- the fantasies don't create that damage, but they can aggravate it and sometimes disastrously trigger it. It's unfair to assume fantasy is always a direct precursor or indicator of reality, but it's naive to treat them as completely separate and unconnected; one has to get down to brass tacks about specific people before one can make judgements in either direction this way.
TBP's error, as above, is to think it's both possible and morally obligatory to prevent people taking the discussion of fantasy topics to unhealthy directions or extremes by prohibiting any discussion of all of certain topics, on the grounds there can't possibly be enough "healthy" use of them to justify permitting it even in a fantasy environment. This, again, I reject on the grounds that it's a pre-emptive assumption of the worst possible context, without taking specific individuals into account.