Has he made a public comment on this? The only reporting I have seen has been third hand. I am taking the reporting at its word, which is that he did an analysis using alternative dependent variables that showed no significant difference. I'm also asserting that his analysis is more likely to be flawed than the original study, since promotion level is not clearly an independent variable whereas Facebook tenure is.

If the facebook engineering department is biased against women, they are likely to both promote deserving women less and reject their code more. If you do an analysis using promotion level to predict code rejection, you may not see any evidence of bias in this scenario, no matter how severe it actually is. Do you disagree with this possibility? Can you point me to anything that Facebook has said or done that explains why they are not concerned about it?