I am sorry to hear this happened to your friend, Leonard. 20 years faithful service isn't taken into account if you defame or criticize your employer online. The same thing happened to my son. He posted something online about his employer (he thought privately) and one of his coworkers shared it. So, my son was stood down for months and eventually put off.

We all need to be careful what we post online. I have heard people applying for jobs missing out because the prospective employer checked their social media history etc.