More specifically, they would be not affiliated with USAT. There is no WTF club membership or affiliation.There are many large tkd clubs (with literally thousands of members) who spar using olympic tkd ruleset but are not affiliated with the kukkiwon/WTF and therefore are unable to compete in the olympics. Many clubs were once affiliated years ago but chose to discontinue their affiliation due to the direction kukkiwon tkd was heading but still spar using the the same ruleset.
Same goes for the Kukkiwon. There is no club affiliation. You either use the Kukkiwon for certification or you don't.
Daniel