Kalen, you can call whatever you want a cape, and "cape" would be a correct adjective for a green sticking out into water and surrounded by water on three sides.
But as CBM used and applied the term to golf holes, he apparently pictured a green not normally reachable from the tee. Remember that these were much more than just rote physical descriptions, the were underlying strategic concepts, and the strategy in the hole involves calculating the best approach and executing the shot to get it.
As for CPC 16th, for reasons I explained above to Gib, I am not quite seeing it, but it is certainly within the realm of reasonable.
As I intimated to Gib, I agree with you regarding CPC 17th. The green juts out perpendicular to the general line of play, and while it isn't surrounded by water on three sides it is surrounded by water on two sides and a nasty bunker on the third. Plus, the consideratons off the tee are consistent with the cape.
CPC's 9th has cape qualities as well.