No one was restricting anything. Air Canada did not force them to be at work, or apply for the job. They understood what THEY were signing on to when the applied and accepted the position.

The company has a policy on how customers should be treated. By violating that policy, they were suspended.

They were free to voice their opinion that is their right. They were however also responsible to their employer and any liabilities resulting from the agreement THEY signed to get that job.

In all labour issues there are two sides, but in this case, an employee violated rules set out by the company that the employee agreed to. The suspension was more than justified, which is obvious considering the union is not attempting to fight it.