Correction. Kerry did not serve even 1 tour of duty.
A Tour of Duty was 365 days. Count 'em. 1 Year!
Kerry had 2 assignments. Period. Quite a bit of difference.
It would be incorrect to say that someone taken from the field of battle either dead or disabled had not served a "tour in Viet Nam".
So anyone who was wounded seriously enough to be sent home after less than 1 year did not serve a tour of duty? I don't think so.
(Not that Kerry fits this category, I am simply disputing this unnecessarily strict interpretation of the term.)