A suit and tie can convey a sense of professionalism and authority for a security officer. It can also help to create a more formal and serious image, which can be useful in defusing potentially volatile situations.
Wearing a suit and tie can also serve as a visual deterrent, as it can indicate that the security officer is prepared to handle any situation that may arise. Additionally, it is a way to show respect for the place or the people they are serving and protect.