This is a court of law not an open policy debate
Registration is reasonable? Machine guns aren't necessarily protected?
This is a legal battle NOT an open debate about the merits of gun control. From a legal stand-point no one trying to maintain credibility before a panel of diverse political views and deep breath of legal precedent would try to argue otherwise. Legally
of course registration is reasonable. Legally
of course machines guns aren't necessarily protected. Why? Because the courts have
already ruled so in the past and a big part of legal analysis is deference to prior precedent.
Gura wants to show a total ban on handguns is unconstitutional. It's not in his interest- or ours- to try and overturn countless laws on the books with a presumption of constitutionality. Judges are legally conservative by nature and will rarely take such large steps forward without caselaw foundation to stand on. As every commentator notes, it's been 70 years since a decision, so absent "activist judges" it's baby-steps all the way.
Consider the road to Brown v. Board. Houston's team couldn't start out and say "Separate But Equal is Per Se Unconstitutional" and expected to win after decades of precedent establishing legalized discrimination & Jim Crow laws. Charles H. Houston had a strategy of tearing down Jim Crow by building a new body of precedent, starting first by demanding equality even under the Separate But Equal regime. Gradually, in the context of higher education, it became clear separation was unequal and Houston could attack primary education. But even with a landmark decision such as Brown, SCOTUS required states move only with "all deliberate speed."
For gun control, something embraced by the international community and much of this nation if not a plurality of "elites" here, you won't get a ruling as shaking as Brown without groundwork first and even then it will move only with "deliberate speed". For such a legal uphill battle, you need to wisely pick your fights to win a war of attrition. Trying to move faster than the court is willing to go means you gain no ground at all.
In a legal vacuum lacking more than 70 years, you want to stick to your singular legal point with laser-like focus. Any rhetorical non-legal arguments will weaken the strength of your legal argument.
For those of you wanting more rhetoric, imagine debating a pro-control individual SOLELY on issue of objective mechanical similarities and differences between different times of guns yet having them continue to introduce arguments about "rivers of blood" and "rising crime". You would roll your eyes and disregard anything they had to say. The "preaching to the choir" rhetoric you guys want has just about as much legal weight in a court of law.