I don't see that part about the seatstay attachment in the rules...or is that one of those ambiguous "implied" rules based on the incomplete "figures"?
Also...can you honestly state that the Felt bayonet fork isn't also an attempt to "skirt" the rules? Hmmm?
Seriously though...sure, there's no tube going through the head tube and so the "nosecone" on that fork is definitely structural, but come on now...the whole idea was to increase the aspect ratio of the section in that area. In other words, it was done for aerodynamics first and foremost. Perhaps there might be some steering stiffness improvements...but, it's not like a "traditional" fork is necessarily not stiff enough.
Lastly, as far as you know, according to the UCI does the seatpost need to be in line with the seat tube? If not, that could explain your confusion over the curved seattubes fitting within the template (along with the seatstay junctions and the extra material allowed at the fillets).
In the end though, IMHO it still remains that the only people to blame in all of this are the writers of the rules. If they had done a better and clearer job in the first place, a LOT of this uncertainty wouldn't have been present and the need for "clarifications" wouldn't have occurred.