Kind of getting off topic here but if Web Environment Integrity takes off then the whole issue is that its then up to the website if you're even allowed to use Firefox.
Any company in the US that tries that is going to run afoul of the ADA.
I'm not sure... Are you saying Firefox is the only ADA compliant browser? Years ago when I dealt with ADA and web accessibility I found gaps across all the browsers. There wasn't a one-size fits all. Rather mileage varied with each website.
Have things changed?
I'm saying forcing use of Chrome means specialty user agent's with accessibility features won't work any more than Firefox.