Trump took the advise from the NRA to have the atf re-evaluate bumpstocks after the las vegas shooting.
It's the atf that does not following the definition of the law to re-classify them.
You should ask why, when 'republicans' controlled the house and senate, why they didn't advance more pro firearm legislation.

Donald J. Trump @realDonaldTrump
Obama Administration legalized bump stocks. BAD IDEA. As I promised, today the Department of Justice will issue the rule banning BUMP STOCKS with a mandated comment period. We will BAN all devices that turn legal weapons into illegal machine guns. 4:50 PM · Mar 23, 2018.
Personally as life member for more than 50 years, I kind of doubt that the NRA had anything to do with the ban.
You don’t know what you are talking about. The bump stock ban was done by Trump. Promotion of red flag laws was done by Trump. His record on gun rights, or violations we should say, surpassed Obama.
Oh yeah?
Trump says he is ‘writing out’ bump stocks
“Bump stocks, we are writing that out. I am writing that out,” he said, addressing a group of state governors at the White House. “I don’t care if Congress does it or not, I’m writing it out myself.
Trump also said bump stocks should be put into the same category as certain firearms, making it “tough” to get them.
“You do a rule, have to wait 90 days,” he said. “That’s sort of what’s happening with bump stocks. It’s gone, don’t worry about it. It’s gone, essentially gone, because we are going to make it so tough, you’re not going to be able to get them. Nobody’s going to want them anyway.”
He signed an EO banning them... Look it up. It was overturned by the courts in 2021.
what bs
Re: 4 - Eh. Using this line of reasoning, a President could slough off any responsibility by claiming an advocacy group advised him to do this or that.
President Trump directed that review be done. That was his agency. And his decision to request that review.
Trump took the advise from the NRA to have the atf re-evaluate bumpstocks after the las vegas shooting.
Just take the 'L' bro. Trump banned them.