You seem to have a problem with both democracy and the Constitution. In a democracy, folks can vote with whomever they want for whatever reasons they choose, or no reasons at all. In the Constitution are provisions about the rights of the people to petition their elected representatives, and to speak freely and publicly about the political issues of the day. The NRA is merely the expression of voters whom you don't respect exercising their Constitutional rights in a manner that frustrates your political interests.
Why are you attacking his constitutional right to express his opinion?