There's an idiot politician named Mallard

who decided to signal her virtue and caring(like some other idiots) by cutting up a AR-15.  Creating an illegal SBR in the process.  And when various people pointed out the violation of federal law, she called them 'NRA trolls' and "No, I didn't, and I turned it over to the police, so there!"

Except she did.  And the follow-on effects are likely to be interesting.
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.
Yep.  Interesting quandary for the BATFEIEIO: if they do prosecute, all their usual supporters will have fits because "No intent!  Artistic expression!" and such; if they don't, then anybody they've screwed with for accidentally being a fraction of an inch below the legal minimum is going to have their lawyer beating on the door of a judge.

This could get real interesting.

Note she has the usual slanderous crap to throw out(“Why are you more outraged about me taking a gun out of circulation than about our children being murdered in our schools?”) when the problem is her breaking federal law without a second thought.