Interestingly I think this brings up a valid point that she made - when you hold the voice of someone as truth because of some particular identity they have, it becomes difficult to criticize them as wrong when they say something that doesn't really make any sense.

You see, she wasn't complaining just that she felt silenced here, but that she felt people were speaking for her (i.e. kind of how we're doing now), and that people considered her and other with disabilities marginalized, as if they can speak for them.

What this means is that she sees your comment and my comment here specifically as a bad thing.

Which is utter nonsense. Marginalization isn't some purely subjective experience. You can't wake up one day in your suburban home and say "I'm marginalized". That's just not how it works. Marginalization is when you've been striped in some way of your ability to function in our society. An example would be the mental health system that made it impossible for either of my parents, both who deal with schizophrenia, to find stable work. The society around them marginalizes them, it strips them of their power to function in our society. Their experience in our society is very real, and as such I can talk about it regardless of whether or not I have schizophrenia. They may not believe that they're marginalized but it's very plain to me that they are, all hard evidence is there. And I don't like living in a world where that exists, so I point it out every chance I can.

By her reasoning I shouldn't speak about the marginalization of my parents and all those treated wrongfully for having a disability, because I would somehow be speaking for them. And that's why I think it's important to remember, regardless of a persons life experiences and identity, they can be completely wrong. They can say things that just don't make any sense.