It's actually the best thing they can do for the Right to Keep and Bear Arms. (Well, other than support the Constitution, but we all know liberals are incapable of that.)
By doing so they demonstrate:
That they don't know enough about firearms to render one inoperable.  They keep chopping the middle of the barrel, leaving the receiver, bolt assembly and fire control mechanism intact, so it still shoots bullets. And no, I'm not "Gunsplaining" (per some gamma cuck who apparently got into the Marines).  I'm EDUCATING you. Because if you have no fucking clue how a firearm works, then your opinion on the matter is on par with a "Car safety" activist who doesn't know the difference between an engine and a transaxle.
AND in the process, creating an illegal sawed off rifle.  Which shows that:
They aren't even aware of the National Firearm Act of 1934--one of the oldest federal firearm laws, and most important (per their arguments). And if you have no fucking clue what laws are already on the books, then you should learn that before you start publicly masturbating for more.
That they believe "intent" matters for the NFA. Now, I'd actually like to see them accomplish this--it would reduce the power of that complete Fascist regulation. But if they aren't aware they're actually making points for our side, they should continue doing so. Thanks, fucktards.
That the NFA is obviously irrelevant, because even you, gun hater, thought it was perfectly okay to violate it and are defensive about doing so. "I didn't MEAN to be a criminal!" Yeah, you know how many innocent people have been trapped with that crap? Who never harmed anyone?
That telling the police they're going to break the law makes it okay--sort of like if they started a meth lab, but informed the police first. It just proves that the NFA is a complete pile of shit. Did I already say that? Well, it should be said again.
And that they believe they're too unstable to be trusted with a gun. "This gun will never harm anyone!" Neither will any of mine.  In my case, it's because I'm stable. If you're afraid yours will hurt someone, it means you believe the operator--yourself--is the problem.  So at least you got that part right. I'm actually totally cool with a ban on liberals having access to dangerous weapons, like firearms and ballots.
And if ATF doesn't follow up, then they've helped weaken the NFA. Thanks. That's actually a good thing. Every video of someone violating the NFA and not getting punished is an affirmative defense down the road. Of course, sawing off, rather than milling or turning a short barrel, is usually a criminal trick. So you've helped all their legal defenses, but then, no one ever claimed you were smart.  I know, I'm "gunsplaining" again.
If the BATFEces do follow up, the chopper is going to jail. Also a good thing.
So yes, let's encourage more Democrats to chop up their weapons, making normal people safer, and nibbling away at their previous bullshit law, which is such bullshit they instinctively recognize it's pointless, but want to pass something else.
You know what they say about people who keep repeating the same actions, expecting different results?
They're insane, and therefore shouldn't have access to firearms.
PS: Oh, yeah, and every one they cut up will be replaced within minutes by the quiet professionals of our firearm industry.