False. Ability to do so and support of government isn’t the same as legal.
Legal by law and legal by practice have the same effect on citizens.
ATF has been given the ability to make rules on various topics. Attempts to overturn these rules are almost as difficult as attempts to repeal laws. The bump-stock ruling by ATF is a legal rule, until they change the rule.
Try going to court with the argument that an ATF rule isn't legal.
Purely a case of semantics. We may not like it, but it is what it is.