There were a few different encoding schemes we used when I worked in DEC's Small Systems Group. It wasn't necessary to explain all of them in the article to make the point that on non-byte-addressable machines it was more cumbersome to write software to manipulate text than on byte-addressable machines.
When we could live with only uppercase letters, digits and a very few punctuation characters, we used a 6-bit encoding scheme called RAD50. But when we needed a fuller set of punctuation characters or lowercase letters, we used an 8-bit encoding which was 7-bit ASCII plus parity.
As for Gosling Emacs, I heard stories back then that Gosling had incorporated other programmers' contributions (including Stallman's) into his version of Emacs, and then sold it to Unipress who treated it as proprietary and violated the programmer's tradition of sharing code. Since Stallman hadn't included a copyright in the code he contributed, it was in the public domain so Unipress could claim proprietary rights to it. This is part of what made Stallman decide to copyright his later code and invent a license that would require recipients to behave better than Gosling and Unipress had done.