There is nothing inconsistent about the prisoners being offered to Yoren by Ned, as:
1 - there is nothing that confirms any particular prisoners were offered by Ned to Yoren; and
2- even if they were, that does not prevent Syrio from slipping into the dungeons or even into Yoren’s wagon and performed a switcheroo at any time.
So, in fairness, it’s all possible. To be clear, I don’t particularly believe in it, but it is admittedly quite possible.
BTW, on the S=J front, for those not closely watching episode 08, there is what appears to be a pointless 10 second scene just before the final throne room scene in the episode. In this “pointless” 10 second scene, we see a nameless, faceless, guard walk through Ned’s cell for no reason whatsoever, give him a mild kick and heading down a hall with a torch in hand. The guard is on the screen for a few seconds at most.
The question is: why was this brief scene included at all?
In the books, Ned was in the Black Cells, had a private cell which was small and behind a solid, thick oak door. There was no reason to walk into Ned’s cell whatsoever.
In the TV series, it appears that a guard who was heading down the gallery (although Eddard is the only prisoner in the Black Cells at this time) for no apparent reason. Again, no good reason to show this totally innocuous scene to the audience – unless it wasn’t innocuous at all.
And that’s the point: why they even bothered to show such a brief throwaway scene? We already know Ned is in the dungeons at that point in the episode. We have already seen Varys visit him and Tywin has confirmed Ned is in chains and will not be released.
Yet, they show us this scene anyway, for reasons unknown. It may be argued that the small scene simply provides a reminder to the viewer of Ned’s predicament just before the final court scene where Sansa begs for her father’s life. I suppose this is possible – though it seems quite unnecessary at that point.
The Syrio=Jaqen conspiracy theorists can justify that the “guard” was Syrio the Faceless Man, heading down to the cells to find Jaqen and do the switch. The reason they showed it was to provide a clue to careful viewers that somebody, presumably in disguise, is tramping around down in the dungeons who shouldn’t be there.
I don’t put much stock in the Syrio = Jaqen theory, but it was a very odd thing to show in an episode where screen time was closely budgeted by GRRM. Yet GRRM wanted us to see this very brief “throwaway scene”. Why?
I would also add that the book never had Syrio talking about any aspect of the Many Faced God of Death. Syrio never does it – not even once. Yet in the series, Syrio does – and often. It’s not as is there are no other gods in Bravos for Syrio to worship or pay heed to. Bravos has temples to HUNDREDS of gods there. The House of Black and White is just one of many. Yet in the TV series, Syrio repeatedly quotes the God of Death.
My point: All of the foregoing is some evidence that Syrio = Jaqen is a real possibility.
Or, it is evidence that GRRM just enjoys fucking with us, from time to time. :P