Mr. Halls was not an employee who was terminated.  

He was a personal services contractor.  Under that contract, the contract could be ended, without cause, with 30 days notice.

That is what happened.

He was being considered to work as an instructor of some sort; that could have been as an employee or as a contractor.

No one has a 'right' to get a job; no one has a 'right' to have a contract in perpetuity, especially one that specifically allows its end "without cause".