Im sure this wasn't the only thing used for the eviction but if it was that is clearly over the line. With that being said, the behavior is disgusting and if I was in a building dealing with such, I wouldn't feel bad to see them go.
Having lived in such a situation before, I could find globs of spit, blood, and who knows what else on elevator buttons, door handles, mailboxes, and entry buzzers. It's disgusting and incredibly unhealthy. It's also discrimination towards people with germ related phobias or disorders.