It made sense to me when I took the commands the Origins characters give to Richtofen out of the context of the trailer.
Time stops when the Origins characters appear at Der Riese, that explains the clock looping the 3 same seconds.
They've learned about original Richtofen somehow, and are there to reset his timeline and the commands they give to him are their way of doing that.
"That's why you better do exactly what we say"
The commands they give make it seem like they don't want him to open the teleporter but that was their plan, when original Richtofen dies the timeline restarts, the commands they give now will stick with him when the timeline restarts.
"great evil approaches, there are a chain of events that must be set in motion" - the chain of events through locking Sam and Maxis in the tele to Moon
"you must awaken the test subjects" releasing Takeo, Dempsey and Nikolai to help him complete the chain of events
"Richtofen, whatever you're thinking of doing, don't do it" - in the context of the trailer it makes it sound like they don't want him to open the door, but what they mean is that they don't want him to go through with the plans that we've seen happen from the moment he locks Maxis and Sam in the teleporter all the way to Moon
"you do not want to meet what's on the other side of that door" - the great evil, the version of Richtofen that will exist if he does go through with his plans
"you can not begin to comprehend the greater evil you will unleash" - pretty much the same thing, Richtofen thinks having so much power would be good right now, but what will really happen will be bad for him too
and as soon as Richtofen is dead his timeline restarts, he's right back at that moment he locks Sam and Maxis in the teleporter but his ideas have changed because of what the Origins characters told him.
They never told him not to open the door, they just told him not to meet what's on the other side of it.