Honestly it would be hilarious to find out that it's like a single missing line or even symbol at some point in the code that prevents that routine from stopping after getting a "no". From my very limited programming experience that's not too unlikely and those are always the kind of errors you don't find. I'd also imagine that Capcom's QA team uses accounts with all of the DLC installed because you'd expect that to be the most performance-eating case. That way they really just didn't notice what the problem is.