I think the Crimson Moon was just Shiki looking so deep that he was about to touch on the truth of it all. I'd be surprised if this doesn't come up again. Wasn't Shiki doing something weird with Nero back in the OG too? He was like reading his thoughts or something. The retrocognition on Vlov might be some extension of that.
Even if Mario isn't wrong about forming your own idea blood, it might just be the 27 are something even more special.
Speaking of Nero, I wonder if the beast Vlov killed outside the estate may have been one of Nero's?