Earlier quoted context omitted.
It matters because the memo as being portrayed as 'the opinion of Google' by websites looking for clicks. The opinion is as relevant or not as any opinion expressed on Hacker News, the fact that the person who expressed it works for Google is irrelevant.
Well, there a honest opinion of an unbiased engineer, ideally a researcher who was trained to filter his own biases, from the inside of the organization , speaking honesty is likely the best approximation that you can get for “an opinion of Google”. It is important that the engineer is an insider, as from outside of Google access to its internal knowledge is limited.
Also, the document we're discussing was not written as a serious research paper. It's a more like one of Steve Yegge's rants, written to be provocative.
When something Yegge wrote while at Google leaked, people knew who he was, so it was interpreted as "here's what Yegge thinks." It's the same in this case, but it's someone else who isn't famous.