Interesting blog post. It's something I encounter at work. The editors at my company used to use words like "wheelchair bound" or "mentally ill" before people with disabilities complained and now we make sure our legal products all refer o them as a person who uses a wheel chair and a person with a mental illness. Its too much of a label otherwise and its dehumanizing to call them anything else.
One reason many people that use wheelchairs don't like terms like "wheelchair-bound" or "confined to a wheelchair" is because, not only are they not truly bound to their chair, they don't feel confined or restricted by the chair. The chair allows them to go places and do things they would not otherwise be able to do. The chair is liberating for them, not confining.
I mean I wear glasses but am I bound to them? No. And I've been diagnosed with depression so I guess I'm a person with a mental illness but I don't consider myself mentally ill. There's a huge difference.