Here's what you missed from your own quote.
“The NRA believes that terrorists should not be allowed to purchase or possess firearms, period. Anyone on a terror watchlist who tries to buy a gun should be thoroughly investigated by the FBI and the sale delayed while the investigation is ongoing,” Cox said in the statement.
“If an investigation uncovers evidence of terrorist activity or involvement, the government should be allowed to immediately go to court, block the sale, and arrest the terrorist,” he continued. “At the same time, due process protections should be put in place that allow law-abiding Americans who are wrongly put on a watchlist to be removed.”
So Trump's position, which is equivalent to Rahm Emmanuel's position, is for a gun ban for anyone on the terror watch list. The NRA's position is for a delay of the sale while the government investigates to see if the person has actually committed a crime. If the person has committed a crime, then prosecute him. If he's convicted, and his conviction is a felony, then he's lost his right to bear arms through due process. Trump said nothing about due process or a "delay" in his tweet. Of course if enough people put pressure on him he will "qualify" his statement to be more in line with the NRA (not that I actually trust the NRA to protect gun rights either) and that is what I'm hoping for. We must keep the pressure on this charlatan. He is the GOP nominee. The advantage over Hillary, and it's a small advantage, is that he actually needs people who support the 2nd amendment to vote for him. Thus he might be persuaded to do the right thing. But if people like you keep insisting on making excuses for him, the pressure needed for him to do the right thing will dissipate. Quit making excuses for the man. Hold his feet to the fire. That's our only hope.