I guess my whole point is, typically when you have a contract with an open-ended provision stipulating future amendments, it is understood in contract law that the amendments have to bear some reasonable resemblance to the current provisions in the contract.
For example, let's say I contract to paint your house, and a provision specifies that I will inform you of any "supplies which I require during the provision of services," and that you have to provide those supplies. For the first few days, I ask for paint, brushes, and a ladder. Then, on day five, I tell you that I need a new SUV, a diamond necklace, and six tons of caviar. You don't have to provide those things, because they don't bear a reasonable relationship to the pre-existing terms of the contract back when it was signed. The new amendment, requiring you to provide these "supplies," is outside the scope of the original agreement. I did not INTEND to agree to those KINDS of provisions.
That was an exaggerated example, but I think you could make a similar argument on the HOA's ban on guns. I think you could argue that, when the person signed up for the HOA, they did not intend to sign away their right to bear arms (or any other Constitutional right, for that matter). I think you could argue that the ban on guns was outside of the scope of the original agreement, and that the amendment to the HOA contract (the new rule) should not be enforceable.
Everything make sense? Number 6, any other hateful comments? You still haven't told us what you do for a living...