yours is a provocative question, jeff, because the people who favor hybrids often claim some babies can't be distinguished from the "real" thing, or -- my favorite -- "after two (or four) generations the babies are pure again". I think the parents' appearance will tell a lot; the appearance of subsequent generations from these albinos bred x each other might be even more revealing.
But the good news is the meristics are significantly diff between campbelli and ruthveni, at least according to Markel. Is that considered a good source for that information? If the scale counts he gives are correct there are any number of differences that could indicate whether the animals are pure. I didn't check the meristics for nelsoni, so i don't know whether there are differences between them and campbelli sufficient for differentiation.
Like you, I hope these babies are pure. Campbelli is a neat animal. There are hypos, of course, this would be a nice addition, would undoubtedly increase the subspecie's well-deserved popularity. And it would be a nice stroke of luck for the breeder--what many people undoubtedly hope for* ! It'll be interesting to see how the story unfolds, pix, etc.
terry
* -- tops on my own "wish list"--the emergence of white-side morphs in triangulum. We've seen it in Pituophis, Elaphe obsolete, L. getulus, seems reasonable to think it might show up in triangulum eventually.