There is a Joseph A. Michaud buried in the St Francis Catholic Cemetery in Waterville, ME 04901
b.Nov 11, 1934 d.Jun 29, 2002
Listed in National Cemetery database he was a PFC in the Army. Served 1957 to 1959 according to Dept of VA BIRLS.

The only Joseph Michaud that is listed in U.S. Marine Corp Muster Roll on Ancestry (that served during KW) looks to have been in service by Oct 1, 1949 and maybe earlier. Also listed with JR with name. Joseph Alfred would have been only 15 yrs old or younger. The Joseph in the Muster Roll has serial # 637817 starting Oct 49 then and ending Jan 1952.
A different Joseph Michaud with different Serial # in the Rolls April 1955 after the Korean War.

In transcriptions of records names can be transcribed wrong and indexes do miss people. So 1940 Michaud could be Michand or Michond or Michoud or that Joseph is not in the index at all.
How do you know he was born in US?
Good Luck....his death certificate should have parents names and if a Veteran.