Nor does his headstone at Arlington
David McCampbell, Captain, United States Navy
Look, just because the middle initial "S" appears somewhere on the internet does not make it so.
I can show you places on the internet where folks who by all appearances seem to know what they are talking about will tell you that the F6F was designed after a thorough examination of a captured A6M2, but that doesn't make it so . . . and repeating the tale doesn't make it so either.
Mistakes feeding on mistakes . . . the bane of the internet.
I sometimes find, in both internet and print, my father's middle name listed as "H" when it is "N"; this stuff happens. And it sometimes occurs in what some, including myself, would classify as relatively authoritative books by folks who generally know what they are talking about.
I wouldn't trust my master's thesis to Wikipedia if I were you. The site you provided for USS McCampbell showing the initial S and the, note, retyped, citiation, also with the initial S mean nothing. My bet someone said "Mr. Beknots . . . you and your people go and develop an approvable website for the ship." And Beknots says to his saviest geek, "go forth and create a web site and let me know when you're done" And the geek says to himself "Does McCampbell have a middle name? Better check . . . fire up the internet!"
Websites, be they USN official or the great satan Wikipedia using the S middle initial are merely repeating a mistake.
Arlington always has middle initials.
USNA Register always has either middle name or middle initial. The name that one uses when one matriculates. The rare exceptions where someone has changed his/her name . . . the new name is listed after the matriculating name.
Look at this from the USN Historical Center . . . The Naval Aviation Hall of Honor, famous US Naval Aviators enshrined at Pensacola's National Museum of Naval Aviation. look at year group 1988:
http://www.history.navy.mil/avh-1910/APP19.PDF
Or the National Aviation Hall of Fame in Dayton:
Aviation Hall of Fame - January 1997 Air Force Magazine - Vol. 80 No. 1
Or the US Naval Academy:
USNA Honorable Graduates - Medal of Honor Recipients
Or the Alabama Aviation Hall of Fame:
Alabama Aviation Hall of Fame Inductee
(Click on the AAHF logo to see the plaque)
Need I continue?
Rich