dude_bro
Essentially, these companies are probably just contributing to the thing they are against. But I guess so long as their hands aren't getting dirty they get to pretend like they're doing the right thing and taking the moral high ground.
It's a harsh realization that many grad students come to, but unless your grad student is getting some level of results then the advisor will feel his/her grant money isn't going to good use. It's essentially the same thought process a manager goes through when they feel they are paying somebody a salary but that person is not contributing.
This is why independence is so critical and one of the most important traits of a grad student. Time spent telling a student exactly what to do, again, is not always a resource well spent.
Anyways, this is just my perspective on things based on conversations with a couple of my immediate family members who are professors. I went into the normal job market after getting my bachelor's, and I see a lot of parallels between the world of academia and the rest of us. There are different titles and the work is different, but much of the structure and politics are the same.
This was at a very large corporation, and he had been blind throughout his long career there. I believe the primary tools he used were JAWS and a device that would actually generate braille for text on screen. This was pretty incredible to me, as he would do most of his reading via this braille device.
I don't think you will be limited to a certain portion of the stack. In some ways, it may open up certain opportunities like working more on the Accessbility features for front-ends, which is a critical part of a front-end but often overlooked.