I think what Bernie probably meant (I hope anyway), is that NAM's are more likely to be poor than whites or Asians, on a per capita basis, and thus issues of poverty, imprisonment, crime, social dysfunctionality impact them on average more than people from wealthier races.
I think it's more likely that he's an old white dude trying and failing to speak the language of his young progressive base. I think it's a good thing that he (and Clinton) are talking about things like white privilege, intersectionality, etc. on the campaign trail but it's obvious that they're just parroting talking points they've probably been debriefed on by their advisers. At a fundamental level, I'd be shocked if either Sanders or Clinton really "get" it, and clumsy statements like this are revealing.