I don't have time for children. Find something better to do.
This is all dumb anyway. You've fundamentally misunderstood what installing XCI's actually does. It simply takes the content of the XCI, converts it to an NSP and then installs it. Installing an XCI has just as much risk and installing an NSP. The only difference is the XCI converted to NSP install doesn't install a ticket since it's not title key encrypted. But it's the ticket that makes a digitally installed game "legitimate". So both common ticket NSP and converted XCI's installed as NSPs are ban risks.
Also, the original point made about not needing patches if you had a legal backup wasn't about court legality, they meant that a legal backup would have a legitimate ticket that was properly signed by Nintendo, issued to the console and NNID of the console you were installing the backup to, which XCI installs are not. Hence why you need patches to play installed XCIs.
Lastly, as for your Betamax argument, you also misunderstood that. The case (which you did not link, you linked an article summarizing it, the actual case is here
https://www.law.cornell.edu/copyright/cases/464_US_417.htm) is whether or not the SALE of a device WHICH COULD record copyrighted content was legal to sell or not. The actual recording of copyrighted content is not address in that case. On top of that, specifically for recording live broadcasts, they are not encrypted content. Now-a-days, digital content is encrypted or protected by some sort of digital rights management for which additional new laws have come out stating it's illegal to circumvent those protections and encryptions even if the sale of a tool to do so is not inherently illegal.
Overall the point is moot, installed XCIs are not different than NSPs, neither are a true backup otherwise you wouldn't need signature patches to run them, you're all pirates, get over it.