Re-reading the SDCC comic after watching a lot of gameplay footage and stuff, there's some details that are starting to fall into place, and other little details that I think are cleverly-hidden spoilers.
This is largely speculation, but I'm going to spoiler-tag it anyway.
Spoiler
The facehugged guy in the comic is the host of the titular Alien, he mentions being affiliated with a character who is mentioned in some gameplay videos as being the guy who (inadvertently) brought the Alien to Sevastopol.
Also in his nightmares, you can see what seems to be the partial silhouette of the LV-426 Derelict obscured in some dust, my prediction is that they went back there, got an egg, dude got facehugged, they put him on ice and brought him to Sevastopol thinking they could save him somehow, and then he gave birth to the Alien and all hell breaks loose.