Whistleblower Firing

The United States Senators are trying to get the right answers from Amazon on their excuse for firing COVID-19 whistleblowers. Now if you are a profitable business and take care of your employee's then why is it a big deal to fire whistleblowers?
Now the more I read this the more that this applies to employee safety. So if Amazon wants to get legal with the Senators then maybe it's time for an OSHA representative to review the companies safety policies throughout the entire company at each and every location.