They’re not plugged.
Obviously, but you’re not getting my point. I stipulated that the barrel be pouted to focus on the bayonet specifically. Why ban bayonets when handguns, for instance, are much worse? If there isn’t a reason to ban bayonetable rifle features without regard to the rifle’s assaultiness, or whatever it is that makes certain guns seem worth banning, then there’s no reason to ban bayonets at all.
All they do, really, is turn rifles into a kind of sword, and last time I checked swords are legal. What is it about adding a knife onto a rifle that interests the government? When was the last time a vicious bayonetting made national headlines? I submit that there is no reason whatsoever. Being able to weld some contraption onto a rifle to feed more rounds without having to reload or tampering with it to render it more fully automatic, those at least I understand.
Not satisfied to ban things most people agree aren’t covered by the 2nd amendment, Congress goes nutty with banning such add-ons—add-ons being easily enough argued into being extraneous to 2nd amendment concerns—until any old extra thing is somehow evil. The reductio ad absurdum of the add-on asterisk to the 2nd amendment is the ban on bayonetable features. It is simply crazy. Where is the anti-bayonet lobby? It doesn’t exist.