BTW IMHO laws passed by Congress regulating or even banning pistol braces and bumpstocks are just a variant on laws regulating and banning machine guns. Whether one thinks that such laws are valid under the Constitution is a matter about which reasonable people could differ...
I disagree with that logic/argument and it goes beyond the Constitutional argument.
Just because a law is passed does not mean it is logical, reasonable, sensible or based on reality. It does not mean that there is a real purpose behind it or that the stated purpose is true.
In this case we are presented with the banning/control of an inanimate object in order to curb violent crime. That is a fools errand.
This type of law, malum prohibitum, comes out of fear, ignorance and dishonesty.