There is no censorship of the NRA's political views, it's just those views are not promulated with tax-exempt donations. Like every other poltical organization.
And like every other political organization, the taxation of donations to them are an abridgement of the right of freedom of speech.
Such taxation is still a clear violation of the prohibition of Congress to make law in such situations.
"Congress shall make no law", that abridges the freedom of speech, press, non-violent assembly and petition.
You still haven't answered my question - should a TV commercial for Tide be taxed?