The powers not delegated to the United States by the Constitution, nor prohibited by it to the States, are reserved to the States respectively, or to the people.
Unless prohibited by law, you have the power to do anything you like. As it probably says in the article, this needs to be law, not ATF opinion.
That wasn’t remotely the basis of the ruling. It was essentially ruled that they don’t meet the definition of a machine gun in the law, which limits what the ATF can do. It was mentioned that congress can amend the law and ban them. They just haven’t.
And there is no constitutional right to bump stocks. They just ruled there is no current law against it. If there was a constitutional right to them, you couldn’t ban them even with a law.