The NRA hasn’t always had a well-thought out position in some respects. They are VERY political, and are willing to give in on certain positions in order to safeguard other things.
It remains to be seen if this compromise was a good one. I agree with the previous poster that it opens the door to the idea that any semi-auto can be turned into a “machine gun” easily - ergo, the semi-autos need to be banned.
But bumpstockj were an endangered species since Las Vegas. Hard to defend something that converts a gun to something else.
I think the President did this to avoid it being inserted into a bill. Then all these a$$holes add conditions, extra bans, anything they want and Trump would either have to veto it (politically dangerous) or pass it.
This gives him a little more control IMHO