Whilst very unethical to pass someone elses work off as your own, AFAIK you would need to prove an actual loss to you caused by the journalist stealing the TR.
Given that it's posted up on a public forum, of which (AFAIK) anthonysimilion has no financial interest in, it would be quite difficult to show an actual loss.
Even admin would have trouble, as whilst anthonysimilion has submitted the TR to AFF, there is nothing preventing anthonysimilion from submitting the work to another 3rd party as well. Admin would have to prove the anthonysimilion has given the full exclusive rights of the work to Admin for publication and that Admin now owns the exclusive rights for that piece of work. For that to stick Admin would have needed to have provided anthonysimilion with some form of payment for the forementioned work.
I don't believe admin takes ownership of all published articles (I was going to check the sign up agreement) as that could make admin legally liable for any information posted here.
Disclaimer - I am not a lawyer, this is based on my own experiences with internet publishing and the advice which my lawyers gave to me for my senario's.