I don't have a trained eye to catch a forgery and don't know a thing about typewriters of that day and their capabilities. But supposedly CBS had them examined. They may be liberal but they wouldn't be stupid enough to pass off fakes like this. That part makes the least sense of anything.
Apparently they were.
I, too, was skeptical this morning, but there seems little doubt now, especially with the testimony of three independent typographers who are familiar with the typewriters of the time.