So you're of the opinion that ANY group can decide some allegation on a whim and go after people stirring up chaos online and in the lives of others?
If not, why do you think that you or your group is different than this ANY group?
An employer can do what they want with their own business as long as it is legally supported, or they could go for it anyway legal or not and have it legally tried if the employee challenges the dismissal.
You as a member of the public can in confidential let the employer know that the employee did something without causing bad publicity for the company should the employer decide let the employee stay.
By stirring up chaos on social media witch hunters are essentially forcing the employers hand, he has to fire the employee or the company and maybe owner/employer personally will suffer bad publicity.