True, but notice how little mention that aspect of the controversy received. Also, the article never said why the initial union worker that caused the entire controversy was fired. Huff post...propaganda at it finest.

The bottom line is in the story adendum:
Management at the Maspeth facility, where employees worked, warned the employees as they were leaving that their jobs were at risk, the spokesperson said. The Teamsters did not immediately respond to a request for comment.

They were warned in advance that they could be fired for the action. They chose to continue. They were fired as warned.
Breaking a contract actually has consequences.