Why the low score?
The obvious problem with this is that the maker didn't stick close enough to the actual events. But movies are for entertainment, and when writers & directors actually get to making a film, they are going to do everything they can think of to make it more appealing. They will invent extra drama and interactions for characters.
Aside from that though, it is a good drama and deserves at least a 6. Crispin Glover is perfect casting for his part.