How so should they be nervous? A lot of other films have kicked in their marketing and take the spot. Better for them to wait and put the trailer out in the right moment. I think the marketing will be quite all right once it starts.
I'm pretty sure already I'm seeing this in cinemas and I will likely avoid any trailers. Photos and posters are good and mostly don't spoil the whole thing. Since this is Wally's first film I'd expect them to throw in quite a lot of the film in the trailer or at least, it wouldn't surprise me.
I think I'm going to skip the trailer. They haven't put out anything like it and since we're pretty close to release, I can hold it Would rather know less than seeing a trailer which shows a lot of the film I'm highly likely seeing in theaters anyway.