FAKE or not, it seems like an awfully big missed opportunity for FOX not to have, at the very least, a teaser floating around for theatres to trail onto STAR WARS in December.
So it would be a huge missed opportunity for FOX to let the flagpole of something like the massive STAR WARS fanbase, not get to see an ALIEN COVENANT teaser.
It might work in theaters to a certain extent but an Alien: Covenant trailer/teaser released online would just get drowned out by the sheer amount of Star Wars hype. There's going to be tons of Rogue One TV Spots, all the various international trailers, film clips, interviews etc...
It would make much more sense to release a Covenant trailer or teaser when the Star Wars fever has died down a bit.
Assassins Creed is also a very good time to show Alien Covenant trailer.
It might get his fans interested in Alien: Covenant but does Fassbender really have such a huge following?