The "lowering the bar" argument assumes there are not enough women or people of color in the population at large who are qualified for any given job. Google's approach probably assumes there are, and puts a burden on the hiring manager and recruiter to find and consider those candidates.
I don't work at Google and am wholly unfamiliar with their internal hiring practices. But in order to prove the author's specific "lowering the bar" claim, we'd need to see data not just on hiring numbers, but on success of the hired cohorts over time. (I'm willing to guess that Google does not try to hire unqualified candidates, period.)
"Lowering the bar" is a dangerous claim that offends the dignity and qualifications of every diverse employee at the company or ever hired by the company. A claim that bold would demand extraordinary evidence, which the author does not convincingly supply, and which I am taking a wild guess does not exist.