FFXIV - Buried Memory (Poster)

[Iscah]

Estinien's black version of the job gear is pretty distinctive (compare to the other picture showing him in Sohm Al), and the dark knight there is clearly Sidurgu's model. If it's not them, it's a pretty odd and distracting choice to just randomly grab their appearances. Maybe Sid is just the default dark knight, since (players aside) he's the only actual known living one left.

I saw a Twitter post the other day commenting on the image, and that person's take was that the image is showing a multiplayer fight and the "player stand-ins" were deliberate lookalikes of the moogle-hating NPCs as an in-joke.

That does seem more likely than it actually being turned into an NPC-assisted fight without any announcement beforehand, and with characters who shouldn't be with you at that point.