I say it's theoretical simply because it's dependent on optional setup. Out of box lightning isn't what super is arguing for. I agree that Supers setup is superior. That doesn't mean that everyone else's ln setup inherits his level of privacy by default. The way it's being argued is as though it's simple, feasible, and done by the majority of ln users as though this isn't a systemic issue. You have to be actively controlling and operating at a high level of opsec going into it:
-Use non-custodial wallets
-Open channels non-publicly (ideally via Tor)
-Route over private peers
-Avoid third-party/invoiced-based interactions
-Never publish node info to network directories
Mind you, Nostr bros are on the higher end of tech savvy, and yet this is beyond most of us. Are we to argue that the best option for the world today is to educate them into perfect opsec on LN, or to give them an option they can get default, high level privacy while they learn how to do it perfectly on lightning?