Right, of course. You'd have to get the activation code or validation thingy or whatever.Yes, it appears that they didn't validate the email addresses, so you could sign up with any properly constructed email address under the sun.....though if you don't have access to that email account, you wouldn't be able to recover passwords or use those kinds of features.
BUT...if you just wanted to eff with someone, you could have signed them up, making it appear as if they had an account, even if they never actually visited the site.
Doodle mentions it because it seems like an angle that many of the prominent folks who get "outed" from this list might try to use, regardless of whether they were in fact the victim of such tomfoolery or were actual paying customers.