Physical touch is not the only type of support you can give someone, these typers are still being supported. When I work with kids I never touch them (unless to play or provide sensory input), but I've taught kids to pronounce sounds they couldn't say and think of words they have forgotten, among many many more. I've worked with adults who lost their ability to spell after having a stroke, and I never touched them but they still learned how to spell target words. We change the way we ask questions (yes/no is easier than multiple choice, which is easier than fill-in-the-blank, which is easier than wh-questions, etc), use gestures, model how to do things, and more--largely without touching any client. That doesn't mean they're independent yet.
Also, if another person is holding the letterboard or iPad as is common in the current FC styles, they are usually moving the board to meet the speller's finger.
I've had many many nonspeaking clients who use their devices to independently ask for something (I want __, I need __) because a previous therapist only worked on that. They can't name objects or describe something or comment, though.
There are very few absolutes in communication, especially with nonspeaking folks. "Not being touched" doesn't necessarily equate to independence. I find these nuances are often lost with FC proponents.