I was assuming that since that possibility wasn't mentioned, that it wasn't. Not always safe to assume though.
It could also be retained sperm, I suppose.
If this is true, I'd definitely like to know about it! It certainly goes against everything I thought I knew about how to produce ivories and BELs.
If you are referring to the sentence where he says "Then I thought, well I guess the female is a yb and lesser x yb does in fact make white snakes", you have interpreted it differently than I did. I thought he meant his thought at the time was that this clutch was proving that lesser x yb can make a white snake, rather than that it had been proven in the past.