What loophole? A boat isn’t going to be any faster if it has a carbon tiller. For all I care you can use a golden tiller with diamond inlay.
We do need to rethink hull weight however. In Denmark a chap made benches of the heaviest hardwood he could find. His benches weighed in at 18 kg. After being scrutinised he took them out and sailed the Nationals grossly underweight but still legal. I think we should have rules that force us to race our boats in the configuration they have been weighed. If we take off something, or add something the boat has to be re-weighed. That prevents messing about with heavy weight stuff while being scrutinised.
If parts are to be replaced by carbon, we should first think about the hull weight rules. Maybe we should weigh the boat with all spars and rigging present?
My personal opinion: Carbon does not add anything, it just breaks faster and if it does it is much harder to repair. If the weight advantage is taken away, I rather stick to alloy that I can bend (back), drill, screw, rivet, weld and what not to extend its life span and/or features.
BTW, any member can propose rule changes. Just send amended rules, as you think they should be, to your Tech-rep who will pass them on to the WIC. After being discussed among the Tech-reps and you the the proposal will be put forward at the AGM. The discussion is usually not so much about the actual proposal but more about the correct legal wording, unless of course you are proposing to make the hull three foot longer. See: Appendix 1. And here is your Tech-rep. The thing to remember is that Tech.reps are hard working people, just like you and me. They will expect you to do the foot work since you are the one that wants the rules changed.