we all know that on most sites you're responsible your the people that you invite. you can get warned, lose your invites or even your account if they misbehave. some sites even disable whole invite trees when one user is a really bad apple.
wouldn't it be logical that you have the right to have them disabled as well?
if you have a cause for suspicion, if you find the user trading or if you don't trust him anymore for any other reason, you should be able to contact staff and have him kicked. if staff refuse to do this, they can't expect you to be responsible for any future actions of the invitee.
is that an option? what do you think?