No, that's not how this works. Firing is for behavior, and an org can decide on its own what standards it wants to set on proof, evidence, etc. of that behavior

No, that's not how this works. Firing is for behavior, and an org can decide on its own what standards it wants to set on proof, evidence, etc. of that behavior, and this is completely independent of whether that behavior is legal as well as the outcome of any prosecution for that behavior. There are legal remedies for "injustices" such as being expelled from a school, being excluded from an organization, being fired from a job, being libeled/slandered or defamed, and so on. This is the way society works and has always worked for thousands of years. The idea that this is "passing sentence without a tribunal" is bunk, these people are not serving sentences, society is choosing how it wants to interact with these individuals, just as it does in countless of other examples.