I don't really have any horse in this race, and it appears that the controversy has mostly been settled. However, I feel the need to give my opinion on this.
While I don't at all support Sirius's vague threats, I generally agree with him on this. It is of course Tork's thread, and he can do with it as he pleases. Furthermore, torn staff agrees with him, making it all very moot. That being said, I do not think that age restricting threads is a good course of action. I have three reasons for this.
The first is simply that our forum is a part of torn, and torn is a PG13 game. If you meet that PG13 requirement, then the game should be open to you.
The second is that I categorically am opposed to age discrimination broadly, especially in a setting such as this, where the game is already PG13 restricted. Why does the thread need to be 18+? Are there going to be 18+ scenes or content? If so, it will be in violation of the game rules. Is it because the author prefers more mature participants? I do not think age is an excellent indicator of maturity, as I have met 45 year olds who are incapable of critical thought, and 12 year olds who are much smarter than I will ever be. If it is due to the setting of plane crash survival being simply too much for children, then I would suggest referencing the extremely popular YA novel, Hatchet.
Third and finally, this is a small forum on a small game. We have worked for years to foster an attitude of acceptance both because it is the right thing to do, and because it is necessary for the forum to have enough participants to meaningfully survive. I have seen the forum effectively dead multiple times, so maybe I have a longer perspective on it than others. Keeping people out of threads because of physical "whats" (IE age/ethnicity/place of residence) about them does nothing to help the forum.
Now, that all being said, if the real reason for the decision was because Sirius is sometimes argumentative and insulting, then that is a different matter. If that is the case, then I feel the adult move is to simply say that, rather than using age as an excuse. That would be a much more acceptable reason to me for excluding him from a thread.
I apologize for sticking my nose into this. I suspect that I will regret it.