I'm basing my assessment on this (from the Washington Post):
Rey was ultimately fired after a confrontation on Aug. 14. Rey, who was shift leader that day, asked one of the servers to complete a task for him. This is where the two sides’ stories diverge. Instead of doing so, the server complained about Rey to the manager, according to Rey’s complaint. Rey believed the server’s refusal to complete the task was disrespectful and inconsiderate to the other servers. He went to the manager’s office, knocked on the door, and — when the manager opened the door — found the server inside. The server “aggressively” told Rey he was not going to do anything else for Rey that evening, according to Rey’s complaint.
But according to emails submitted to the tribunal board by the manager, Rey had been “aggressively” checking on whether the server was doing the assigned task. The server came into the manager’s office, near tears, and said he refused to work with Rey any longer. Then Rey came to the office and started “pushing his way in and talking over her and demanding that the server complete his duties,” Cousineau wrote, citing the manager’s emails. “Mr. Rey came in and started ‘berating and yelling at me for not checking out with him and that he did not sign me out.’ He continued to ‘speak loudly and rudely’ until the manager asked him to leave,” Cousineau wrote, citing the server’s written account of the incident. Rey was fired after the incident, in part because he was “aggressive, rude and disrespectful” to the manager and server, according to the complaint. During his firing, Rey told the general manager that he believed he was being terminated because of his French culture.