He claimed that Google's diversity policy lowered the bar for hiring, how can you read that and not think he was claiming that a portion of his female/minority coworkers were underqualified for their jobs?
This is the full quote, "Hiring practices which can effectively lower the bar for 'diversity' candidates by decreasing the false negative rate." Latter emphasis mine.
I read this the same way that he writes it: that Google takes steps to reduce the false negative rate for diverse candidates but does not take these steps with non-diverse candidates. Policies like re-trying failed phone interviews, or automatically passing resume review for diverse candidates are examples of this (these are examples I've witnessed, I don't know if they in place at Google). They still need to pass the final interview loop, so they're not underqualified. But extra steps earlier in the interview process reduce the false negative rate.
Personally, I think these steps are an acceptable means of getting a more diverse group of candidates but I'd still respect my co-workers if they disagreed. To point out the fact that this results in some non-diverse candidates being denied when they could have gotten offers is factually correct. More importantly, to point this fact out is not to call the diverse candidates passed under such a system underqualified - as I pointed out earlier all candidates pass the final interview loop so all candidates are qualified.
To better illustrate what it means to reduce the false negative rate without admitting underqualified candidates, consider the following scenario:
* Phone interviews have a 50% false negative rate.
* On-site interviews have a 0% false negative rate.
* Neither type of interview has a false positive rate.
* Non-diverse candidates get one phone interview, and if the interview is positive they go on to an on-site interview. If the onsite is positive, the candidate gets an offer.
* Diverse candidates get two phone interviews. If either is positive, they move on to the onsite which, if passes, gets an offer.
In this setup, no candidates are underqualified since there are no false-positives in either the phone interview or the onsite. Non-diverse candidates have a 50% false negative rate; 50% are erroneously disqualified at the phone interview stage. Diverse candidates have a 25% false negative rate. Since they go through two phone interviews, there's only a false negative if both (0.5 * 0.5 = 0.25) phone interviews are false negatives.
He is saying that this is harmful to Google, so he is saying it shouldn't be done, so he is saying that certain people who have been hired should not have been hired.
No matter what qualifiers you put on the statement he is saying that some of his former coworkers should not have been hired.
He also doesn't cite any proof that these hiring policies he is against actually exist, or even define what policies he believes exist. There is just some undefined diversity policy that he is against.
If Google has lowered the bar for women in various ways, why should it be impossible to point that out? Just because some women would be offended by it? So what? Nobody has the right to be offended by facts.
He doesn't back up his claim with any data at all. Where is his supporting data that Google's hiring practices in regards to minorities hurts Google? He's just making a baseless claim that doesn't logically follow from any of the evidence he provides before it.