Serious misconduct as just cause for dismissal practice question

ABC Auto Parts, Inc. employed Xander and Felicia as assembly line workers. One night, during their shift, the company’s security guard discovered them engaging in sexual intercourse on the factory floor, in an area accessible to other employees and during work hours. After investigation and a hearing, ABC Auto Parts dismissed them for serious misconduct. Xander and Felicia sued for illegal dismissal, arguing that their act, while improper, did not amount to serious misconduct justifying termination. Should the dismissal be upheld? Explain.