For example, he was looking into a speech-to-text program in the early 90s because he developed hand problems that prevented him from typing. He was coding GCC at the time, but he decided that he *couldn't* use a proprietary speech-to-text program to allow him to continue writing GCC. He could only use a proprietary speech-to-text program for the purpose of writing a free speech-to-text program.
I.e. he'd use a piece of non-free software only if his use would *directly* liberate others from depending on *that specific* piece of non-free software.
So the exception he accepts is much narrower than what you criticised.
(To finish the anecdote, since he wanted to work on GCC rather than starting a speech-to-text project, he got help from others, including Guy L. Steele, who would type with him over their shoulder dictating code to them.)