[prsimp]

The author addresses the first issue in the paragraph preceding the one you quoted.

As it currently stands, most 'confirmation e-mails' I get also provide an 'if this isn't you' section. All the author is arguing is that we can do away with the confirmation part and keep the 'if this isn't you' part for those edge cases where a person's email address has been used by someone other than said person.

[mgkimsal]

Usually the 'if this isn't you' section says "don't click the link above" or "do nothing and you won't hear from us again".

[Tichy]

But the "if this isn't you" part could be a scam. It would make you click on a link in an email you did not request, which is a bad idea.

[threedaymonk]

That's already the case, isn't it? All emails contain the "if this isn't you part", so the case of the person who didn't request the email is unchanged.