My guess is normal WA BHP's ad (as i know you keep them), but there is no way anyone could possibly tell from simply viewing those pics, or even by viewing the animals. If you can find an albino BHP, breed the two together, then breed the hatchies together, 1 out of every 16 (on average) resulting hatchies should be white and pink/red if they are truly axanthic.
Proving black and white WA BHP's to be axanthic, or not to be axanthic, is something that is well and truly beyond me. Perhaps they are, who knows? How can you prove that an animal cannot make yellow pigments, if their colour/pattern does not require them to produce yellow, it's almost mission impossible. You could breed a WA to a QLD, if all the hatchies showed yellow colours, and then those hatchies were bred back to the WA parent and 50% of the babies were black and white, you'd sure have a good case for proving them to be axanthic.
Another thing to remember, is that just because we can't see yellow in their colours, does not mean they are not producing the yellow pigments, they may be so minute that they are not visible to the naked eye?? I really don't know...