
I do not believe that posting the student's essay in the Free section was the way to go in this instance.
The OP neglected to inform us if he took any other steps to try and collect from the students before he did the posting.
For example, Was he partially paid and only the balance was not paid? Or was a Paypal Dispute filed for a chargeback claim?
There are several factors missing from the conversation that would allow me to support the actions that the OP took. While I understand his desire to collect, seek justice, and also take revenge on the students, I do not applaud the manner by which he accomplished the task.
Sure getting the students expelled would bring him a sense of satisfaction, but then he would still be out financially. I would have tried to use proper channels to collect from the students first.
That is, depending upon the agreed upon payment method. If the OP agreed to deliver the paper without receiving payment first, then he was the one in error because he was a fool to trust the students in that sort of an agreement.