@ Great Dragon - There is no indication of racism or discrimination on that forum thread, nor anything there that would seem to need moderator action.
It is allowed for a clan to state that they are based in a specific timezone or country and only allow members that are in that timezone or country. That is usually done for practical reasons, such as making sure that the members are available at certain times of days for group events, or that all members will understand if the clan chooses to speak in their non-English native language. That seems to be the case with this clan as well, rather than for reasons of discrimination.
If your interaction with them in game, resulted in racist remarks being said, then that should have been reported in game at the time, so that Jagex would have evidence from their own systems to be able to take action. Again, there is no evidence on the forum thread of racism or discrimination.