Meh
CPA is just a Hammerite test. It does what it says on the tin.
OFFICIAL as a classification covers everything from public documents to information under the data protection act. You don't need to use certified equipment for OFFICIAL either.
I think Samsung are just trying to make more of this than it really is.
Samsung = Our phones can be really secure (if you configure them right and have MDM)
CESG = Yes, they're quite secure (if you configure them right and have MDM)
None-the-less the KNOX stuff is interesting from a security standpoint. Now you know it works.