I dunno..the 2nd Amendment isn't "about" hunting, but it certainly proects it. The 1st Amendment isn't "about" porn, but also protects it.
How does the 2nd protect hunting in any way? Your right to bear arms DOESNT in any way relate to a right to shoot animals. It certainly guarantees one the right to own hunting tools, but doesnt do anything to guarantee a right to actually hunt.
Pornography is a form of expression, its a decidedly distastefull form that barely qualifies, but it does nonetheless.
I would complete the analogy with "off-track betting". Off track betting has NOTHING to do with the first amendment, but it does make use of a racing form, which is protected by the first amendment.