I don't know about the incident linked to in the first post. First I heard of it. I did hear of an incident some 10+ years ago where a TKD/HKD school's instructor closed the doors of his school, abandoned it, and left the area suddenly due to accusations of abuse of a 16 year old female student. Again, I don't know specifics since I am not privy to any police investigation that may or may not have taken place. Point being, apparently it does get reported. It is also accepted that it is easy for people to use allegations of sexual abuse as a handy tool to cause an innocent man much trouble.
However, in my opinion, that is a matter for the police and courts to sort out. I think if a student makes such an allegation, it should be reported to the authorities at once. Just as it is "accepted" that false accusations can be made, it is just as "accepted" that abusers will try anything to hide their crime and then will continue to seek victims on which to commit that crime. Rape/sexual abuse is not a thing that real men tolerate. From my experience, women don't think highly of it either. Just as importantly, the law doesn't allow it.
As a society we don't believe it should happen, and we have those laws to use when it happens. One of the ways to prevent it from happening is to ensure it is reported to the authorities when we hear of it. Whatever you may think of police or our judicial system, it is what we have to combat all crime. That includes sexual abuse. It is also the best protection an innocent person has. How many can afford to hire investigators to clear themselves, and get the word to the media?
So to the OP's question, I don't think we as citizens, much less as MA (where other MA are being accused), have any choice but to see allegations are reported to the police. Now, if someone says they heard 3rd or 4th hand of something like that, perhaps it shouldn't be passed on to friends or reported to the police. Each person has to decide for themselves on that, or check the law in their State. At that point is it just malicious rummer or a real incident that has gone unreported to authorities? But if a student, or other under age person reports to you that they have been raped/sexually molested, I think it should be reported. It is difficult sometimes to determine if a victim is better served by being given tools to protect themselves without the public exposure, or come under the protection of courts. But the problem is, how many of us are trained to make that evaluation? If you aren't, and can't defend you actions in court and the press, I suggest you report it.
Again, I suggest people check the law in their State. Some people have a duty under the law to make reports, and can be sanctioned it they don't.