I don't think saying we have a right to own an 11 round pistol magazine is extreme either, and not a single court in the entire country has agreed with that. 
You're still not getting it.
There is a very specific documented conflict in the legal language between the proposed rule 41p about "persons" and trusts, vs. the use of "persons" in the Hughes Amendment. legal opportunities do not come along like this every day.
Yes, I suppose there's standing to file more generic lawsuits over magazine bans, or firearm bans under 2nd Amendment scrutiny/Heller etc. however there are no clear conflicts of written law, and administrative rule-making that pins down the court forcing them to decide, at least in theory in a way that's win-win, no matter what they decide.
Whether opening the MG registry is higher up on the "wants vs. needs" list of RKBA or not as we see it does not play into this. Whether a semi-auto ban or magazine capacity limits is more fundamental to overall RKBA than NFA post-'86 MG's is
irrelevant. It's an issue of the legal logic, the openings in the law that give you the legal advantage period.
The analogy is like one of a civil lawsuit. Say a company defrauded you out of both $10,000 dollars and $1,000,000 dollars in two separate instances. However you've got more in the way of invoices, bank statements, and paperwork proving the $10,000 theft happened, while the $1,000,000 is a more nebulous issue of "he said, she said" for the moment.
Despite the fact that $1,000,000 is so much more money, legally, the best strategy is to go after the $10,000 first, because you're more likely to win, and if/when you do win, you've now created the legal precedent that this company has defrauded you, and more legal remedies may be forthcoming.
Football, it's kicking a field goal on 4th down for a much more guaranteed gain in points, rather than a risky last try at a touchdown.
