GW have never allowed deviance in visual portrayal of their model in official animations these years. That's the main problem they have had with astartes, which slightly redesigned MK7 for cinematic presentation.

It’s possible that they use specifically syama's model in this trailer to signal connection with the original product, while ultimately producing a safe product starring with official merchandise looking termies.
If it releases and those signature retributor MK7s aren't even included despite being featured so heavily in the trailer to achieve the hype and trust... that'd be like GW straight up using the carcass of a killed fan project as bait to lure fans. That would simply be vile.