No, you said they can defy what BZ says because they are more powerful. Madara is way more powerful than BZ, therefore he defies what BZ says about the Yata Mirror /logic.
What you fail to understand (well, not failing, you're trolling, but for the sake of the argument let's go with failing) is that this is a manga, this is not constant whatsover and whatever the author said in the first chapters not necessarily will be held true in the end, cause that's how it works. So far what we seen about the Yata Mirror, about the time it was shown, is that it can properly deflect exploding tags and katana blows, nothing more than that. On the other hand (for comparison) we have seen the Totsuka sword in action, twice, and what has been said about it held true (so far) in the series. So I don't have any doubts that if Madara gets hit with Totsuka it will be drawn into the sword's genjutsu or whatever, but trying to sell that the Yata Mirror is the absolute defense based on what we've seen ... not going to happen.
You just need common sense to analyze what you're reading, that all.