I would argue that the majority of the population isn't interested in finding new ways to circumvent the legal limitations. Those who are generate interest from the bureaucrats in closing down on those fringes and loopholes, particularly when they advertise their ingenuity in trying to find loopholes. It's not going to be worth the hassle and effort for bureaucrats to write new regulations to take care of one or two fringe cases but they will perceive value in writing those regulations when they see YouTube videos and blogs all over the place for dozens (or hundreds or thousands) of people to circumvent the existing regulations and that will lead to more absurdities.
It's pretty damned clear that many people buying "arm braces" for "pistols" are really trying to get SBRs without going through the registration and regulation. A lot of the people talking about it online aren't even trying to pretend that they intend to shoot these AR pistols as pistols so who is really surprised that the bureaucrats are trying to address it? The ones who really need arm braces will be the ones ending up suffering as the tools they need get restricted or banned. I'd rather see a full-frontal attack on the notion of registering or limiting/banning SBRs than all these videos and blogs on attaching "arm braces" to "pistols".