The issue that the author is highlighting is presumably that the imbalance in gender at Amazon is due to tacit discrimination on the part of hirers.
By starting an email in the highlighted manner, Amazon is saying "we're interested in hiring you solely because of your gender, because we feel we have to" which is a little insulting for someone who may well be the most qualified person for the job and implies that the root issue (the discrimination) is actively being ignored.
I'm not offering any solutions here, you may have noticed. Whatever the solution is it's going to involve a lot of compromises and a few deadends. But Amazon's approach here is clearly wide of the mark.