Membership is free.
SSC hats, bags, shirts, jackets. What ISAF intended is not relevant since the language is clear that this requirement applies to all races that use the Racing Rules of Sailing. Moreover, be aware that this requirement started to apply on Jan. 1 and so is in effect right now. Note that under RRS 86.1, no changes in RRS 75.2 are allowed so there is no way to eliminate the membership requirement. Until the ISAF corrects this little problem, you can avoid the protest room by carrying a Scuttlebutt Sailing Club membership card.