I'd be lying if I said I understand how ticketing works. But I do know how blame (in law) and human behaviour works, especially on a colleague basis.
It concerns me (as a non-railway worker) that there is so much ignorance as to what constitutes a valid ticket. It concerns me even more that there are those on here (09065) who seem intent on ignoring the subject matter and placing opinion in front of the facts as presented. For instance; Faced with someone who holds a ticket you are not familiar with, but turns out to be valid, why on Earth would you do anything other than let that passenger continue? You seem to advocate looking for excuses for incredibly poor customer relation behaviour than looking at the fact that the traveller had done nothing wrong!
However, one thing which is almost unbelievable, is the comment from sarahj. Putting aside your use of "gonna" (I'm working on a fair assumption that you are older than 14) What sort of view could you possibly have that you "have a view on this which cannot be shown in a public forum"? Why not? This looks less than a logical statement, as surely you can only have a view which is concurrent with the regulations by which you must stand? You then say "Come on my train and you will see what my view is". Your view is, as it should be, that you will abide by the same rules you expect passengers to abide by.
Between the two of you, you epitomise the very problems RJ faces. You clearly object to his method of ticket use, but to just brush aside the validity of those tickets and concentrate on "us v. him" is rather pathetic. Perhaps if more staff were educated these issues would not arise so easily.
One very simple question; Did he hold a valid ticket? Yes, from what we have been told there is no reason to doubt it. That should be the end of the matter.