My former employer has been contacting current and former employees which were my co-workers and forcing them to remove their personal recommendations for me on linkedin. The empoyer is stating that by recommending me the employees are violating some company policy - which I never heard of. They have threatened to fire one employee unless he removes his recommendation of me from linkedin and they have contacted other employee who has quit 4 months ago and also told him that he needs to remove/modify his recommendation because it violates some agreement that he signed. This is a public traded company - is it legal for them to do this? Is this defamation of character?