He does not commit an error when referencing it; but he can see from posts to the thread that SF is less well known than he supposed!
Perhaps not an error, but the logical argument is
irrelevant to the SF, as it does nothing to support or invalidate it.
If I take the meaning of your double-negative correctly, then no, he is not trying to prove that an optimized character can't be role-played. He says that his view is that optimized characters can be role-played, but he doesn't try to prove that either.
Then you didn't take my meaning correctly. (And are you counting the word "disprove" as part of my so-called double negative? Otherwise, I don't see what you're talking about.)
What he is suggesting is really the mirror case: that unoptimized characters can be role-played.
In most message board discussions I've seen, the reputation for people focused heavily on role-play is that they often make unoptimized, even sub-par characters from a mechanical standpoint. The idea that unoptimized characters can be role-played is a given from both camps, so this addresses a non-existent argument. "You're so worried about role-playing that you don't optimize!" "I role-play so I don't *need* to optimize!"
If that is true, then at times a player's desires WRT their role-play can conflict with their desires WRT optimizing. It is not a false dilemma to say that player must choose one or the other in that case: and SF does not apply.
Sure it does, if only because of its non-absolutist wording. The SF uses the phrase "not necessarily", which implies "but there are cases when it is", such as the situation you describe. Though the dilemma you outline is also not absolutely a "must choose one or the other". If the player does find himself with a conflict between his desire to optimize or role-play, there are degrees of compromise between the two.
The argument addresses the possibility of, not the skill at. Confusion between the two is far more common than I had at first supposed!
No confusion here. I see you're addressing the pool of possible characters. The SF - as you quoted it - specifically refers to "skill at". But it just makes me ask, if your argument doesn't address "skill at", then why even bring the SF up at all?
Perhaps, being more familiar with threads and posts related to SF, you have more information about the intent and discussions behind the statement you quoted. To be clear, when you posted "what SF is really saying", this is what I took it to mean:
"A player's skill at optimizing characters (in general) is not necessarily incompatible with that same player's skill at role-playing (in general)."
and this is what I get your interpretation to be from your postings:
"The level of optimization of any random character is not necessarily incompatible with any possible player's skill at role-playing that particular character."
From there you launched into your sets based on the possible products of character creation, optimized and unoptimized, and the possibility that character can be role-played,
divorced from the concept that it is typically the same player, skilled or unskilled at optimization, that will be doing the role-playing. This lends the entire argument a slant, which in all my years of role-playing and message board discussion, I've never heard, and, from my reading as described above, is irrelevant.
The vast majority of "role vs. roll" discussions is not about whether any random selection from your pool of all possible
characters can be role-played, but about how a particular
person's tendency to optimize or roleplay affects their gaming experience as perceived by others with counter tendencies.
Your "take home point" in the initial post, from my perspective, again addresses an argument which doesn't exist.