The Armslist site makes you click an agreement that you will abide by all laws, and call ATF for clarification of any uncertainties, before it lets you view the site. Not that someone could not lie, obviously.
Will Bloomburg eventually go after Craigslist sellers of autos that are later driven by drunks who killer folks? How about washers and dryers that overheat and burn down homes?
Jerk who apparently knew the sale was illegal went ahead and took a few extra bucks and completed it. He admitted it and is going to jail. I blame Obama and his reckless economic policies, and say the family ought to sue him as well. Heck, he does nmmot need deep pockets - he can just imagine he has the money and it magically is there on the books.
stay safe.