I myself do not care for spoilers, I'll read everything I find, but I'm trying to explain to you that there people such as Skullcruncher who have seen the trailer but still don't want to be spoiled by knowing character names such as the "green guy". And I'm not talking about Dinobots, once you see them you'll immediately know who they are and I'm sure that everyone on this whole planet who is keeping away from spoilers already knows that Dinobots play a role in the 4th movie, that is a spoiler to some that you can't keep away from. But characters such as the guy you previously mentioned and the "green guy" that look totally unlike their G1 counterparts are the ones people try to hide from because they would prefer to find out and introduced to while watching the film, this makes people more excited and eager to watch this movie than oppose to knowing all characters names the movie consists of before ever seeing it.
My main point is that I'm trying to say is people would like to be introduced to those unknown characters during the film, to give them an element of suprise.