I think it comes down to testing and the transition from theory to application. On a phine, so being brief. But if the context for application is theoretical for everyone invilvdd, including the instructors, end results are not guaranteed.
In a traditional karate achool, the emphasis is on learning karate, not self defense. The concern is that people like bill believe they're learning self defense.
End results are never guaranteed. Full stop. There are just too many variables.
Personally, I see no reason to assume that what Bill is learning is any less applicable to self defense than what any of us are learning. Karate (in pretty much any of its various forms) is a valid system of self defense. Now, you may be able to point to a particular technique and reasonably say "I don't think that would do you any good because [blah blah blah]" but even if your objections are correct, that still wouldn't invalidate the usefulness of the system.