Even as a military retired officer, there are only a very few occasions at which I can legally wear the uniform (military funerals, weddings, some parades, certain ceremonies, etc.). I'm not sure about current civilian law, but it used to be a crime to impersonate an officer (or, IIRC, even any military person) by wear of a uniform with the "USA, USAF, or USMC" patch on it. I do sometimes wear the US Army uniform (with "DA Civilian" insignia) as an Emergency Essential Civilian during exercises (and during war, if that were to happen), but it is not allowed for travel or public wear (yes, I also have my CAC and retired ID card). But, back on topic, a TSA official is not an LEO; they have no reason to question the "LT" for wear of the uniform - that's for others.