I assume "verified" means that Ashley Madison's server sent a verification email to that address, and the user at that address clicked on the verification link included in that email.
Certainly, someone might enter in barack.obama@whitehouse.gov for fun. Presumably, emails to that address (and the official public email address, president@whitehouse.gov) get routed somewhere. But who is checking the emails sent to the president's public address? That likely requires a team of people, one of whom might have clicked on the link.
Verification links gets clicked by mail scanning software (for malware, I suppose) all the time - if the GET isn't followed by a POST - the account is flagged valid.
As another data point, one of my gmail addresses is in the dump (Cf. https://xkcd.com/1279/ ) and listed as verified, despite me never clicking any verification link. Then again, I did contact support asking for them to remove my email address from the account (their response was to ask for money) and perhaps that did something.
Certainly, someone might enter in barack.obama@whitehouse.gov for fun. Presumably, emails to that address (and the official public email address, president@whitehouse.gov) get routed somewhere. But who is checking the emails sent to the president's public address? That likely requires a team of people, one of whom might have clicked on the link.