Look, I am not an American, I am not sure what rules you refer to specifically, but I have lot of doubt that a person from protected class would be able to sue if they had a history of abuse.
Right? I think that company either must have had a very bad HR department or there was some other factor besides the ADA tying their hands. I don't believe the ADA would force a company to keep a worker in a job they couldn't (or refused to) do or force a company to keep an abusive employee who was genuinely threatening the safety of other employees. At the worst it might require them to put in the work to properly document the problems, but they should be doing that anyway.
