Well, if that's real, then I'm dropping this, but even if it's just one of those "this is how he feels" things, it's really too far into the realm of absurdity. Guess we'll find out. But this is the magazine version, so it might not make it into the published volume.
Who said it's getting supernatural? All of this could be about some super secret information being passed on through generations that lets them blackmail powerful people or similar. Nothing really says "strongest ninja = strongest fighter."
Guessing Yuuki's or Jurina's father is someone of importance for the overarching plot, and that's the reason for all this fuss around protecting them, this other bodyguard coming to check in on him etc..