People claiming to be a person they are not, and "signing" petitions on Change.Org as somebody else just makes Change.Org look bad when there are fake pseudo-celebrities out there.
Also, it results in more spam in my mailbox when people use my name and email to sign "me" up for random petitions.
And it's just bad form.
Please verify email addresses before allowing people to use them. If somebody enters an email address, send a confirmation to that email that contains some kind of cookie that they need to verify that they actually have access to that email address.