Well yeah, except in the eyes of their employer.
Generally, the only limitations for a private employer firing someone (non-union) is if the termination is based on the employee's race, gender, national origin, disability, religion or age (so long as the employee is at least 40 years old).
Just about everything else is fair game, so long as it's not retaliatory for whistle blowing, but even then, good luck getting your job back.
And most of these have gone through a human resources review, which is just about all the employer needs.
