How is posting factual information and his true feelings damaging to his former employer?
They have no right to stop him from expressing his feelings publicly.
They have no right to stop him from expressing his feelings publicly.
If you get fired and your reaction is to go to your blog and whine about losing email access and not being able to deliver a talk that you had prepared for x time I, as a prospective employer, am going to draw some conclusions about your personality that won't help you get the job I'm offering.