You don't have to kick them...

I would have said something like 'are you here just to do research?' and if they replied in the affirmative then would have said something about feeling uncomfortable about that.

Now that you know that it is unacceptable to the site I don't see why you can't say 'that is unacceptable to this site' and others should back you up if required.

But then I am fairly upfront. It gets me into trouble sometimes....