Please note that in the paragraphs that you quoted Stallman is talking about hardware, not firmware. He tolerates firmware blobs only if they are loaded once to the device and never changed (yes, I know it's more complex than this, read the whole essay for more precise information).
I think this would be a better summary: it's okay for hardware to have code that's baked in at manufacture time and can never be changed thereafter. It's not okay if, after you buy hardware, the manufacturer can modify the code but you can't.
