Let's keep in mind all that we have learned over the last few years.
Most gym jobs are at best contract and many are at will. Unless someone is fired for a reason prohibited by law (i.e., unlawful discrimination), there's not going to be much recourse. There's no union for coaches and as far as I know, the only coaches who might belong to a union would be those in colleges where they are part of a staff union that represents a wide variety of employees. USAG has shown itself to be incapable and/or unwilling to protect whistleblowers, perhaps even to the point of revealing their identities to gyms. The one possibility left open would be filing a report with Child Protective Services, but this would be a lot to expect of a coach, especially if the coach does not know how the parents would react, since parents would necessarily be involved in any investigation. There's also the small nature of the gym employment world in the United States -- especially on the men's side, anyone who coaches in a JO program that competes much beyond L7 probably knows and is known within one degree of relationship by the top coaches in the country. It would take very little to blackball an assistant coach, even more so if you consider that not every assistant coach is readily able to pick up and move to a new area of the country and start afresh if things go bad.
I am not saying people shouldn't try to intervene in bad coaching situations, and we have seen that many have bravely stood up to negative coaching practices. You should, however, think long and hard before judging people who have not done this.