Certainly it is the case that nobody openly admits to attacking free speech. When an employee is reprimanded, removed from normal duties, transferred, demoted or dismissed, the official explanation is invariably that they have not been doing their job properly. There is no ironclad way of proving that suppression of dissent has occurred. However, when a person who has spoken out is treated more harshly than colleagues who, with a similar performance at work, have not criticised procedures or policies, then it is a reasonable inference that dissent is being attacked. Sometimes victimisation is blatant, but there are many more cases of subtle suppression.
Whistleblowers tend to be hardworking and conscientious employees who believe that the system works.
They believe that if they speak out, through the proper channels, that problems of corruption, danger to the public, injustice or discrimination will be addressed. Their disillusionment can be intense. The community loses effective workers and suffers from failure to rectify problems. They are, after all, supposed to be havens of intellectual freedom. This is true to a certain extent, but dissent can be dangerous for academics too.