Right now the email confirmation contains a link to accept the email for the given user.
We do need a rejection link as well, which would immediately invalidate the email making it impossible to accept it by the first link later.
Reason: mailing lists. EvilUser registers, enters email@example.com (or whatever) as email, sends confirmation. He gets the email through the list and confirms. Then sets all email communication to yes.
Then it is possible, naturally, to resend the password and kill the account by logging in, but maybe it's not going to be YOU who logs in fastest, and if you're not the list admin [and the admin is clueless] it could take forever to try to catch the account; and it's a needless hassle anyway.
I see no cons to implement (apart from the time required to code the code). If the recipient is valid, s/he won't reject. If s/he is not valid, s/he definitely not wishing to get more confirmation emails, or anything associated with the imposter.