User blog comment:Bobbs3k/Can Ichigo's New Bankai be stolen?/@comment-11051098-20130630193625/@comment-6342763-20130630233714

I agree, it is also unique in the fact that it also has Quincy power. I doubt those medallions are capable of stealing it. But who knows with Kubo. Could be that Ishida or Yhwach will steal it anyway, though I doubt since then there would be no point in gaining new Zangetsu.