Fake news?
While he was still in high school, Mathers joined the United States Air Force Reserve, in 1966. He appeared as a presenter at the 1967 Emmy Awards ceremony in his dress uniform. After graduating high school in 1967, Mathers continued to serve in the Reserve and made the rank of Sergeant.[9] In December 1969, a rumor began that Mathers was killed in action in the Vietnam War. Although the origin of the rumor is unclear,[10] Mathers never saw action and was never stationed outside of the United States.
More like a bad joke.
Mathers appeared in a "Still the Beaver" TV movie in the 80's, and "New Leave it to Beaver" series shortly after that.
Geez. Beaver getting killed in Viet Nam was a joke about forty years ago.