Soulflayer
Knight of Malice

Would Soulflayer receive Hexproof or Hexproof from White if it exiled Knight of Malice?

I'm thinking that Hexproof is functionally equivalent to Hexproof from Everything.
Concerted Effort wouldn't give creatures Protection from Everything just because a creature had Protection from Red so by the same rationale, I'm thinking the Soulflayer would only get Hexproof from White.

Is that the proper interpretation?

Yes, that's correct. If Soulflayer delves away Knight of Malice, it will have hexproof from white. It will not have straight-up hexproof unless it delves away something with straight-up hexproof.