Sorry, Ant'ny.
"Fred Rogers has been the subject of a few urban legends, among them, ideas that he served in the military around the era of the Vietnam war; was a sniper; was a Navy Seal; or had a drug problem. Rumors to this effect are discounted as being false on urban legend verification websites[2]. Not only is military service not mentioned in any biographies about him, but there wasn't a period of time, unaccounted for, where he could have been involved in such. During most of the Vietnam conflict, he was fully dedicated to his television show Mister Rogers' Neighborhood and before that, around the start of Vietnam, he was working on getting rights for his show and moving it to Pittsburgh."