All the records should be in one place, St. Louis, as the instructions and the title for section I indicate, that information is only for purposed of identifying the individual. In section II he requested an Undeleted report of separation for "all years", which would include the reserve years. But as importantly, it would include his original DD-214 (Report of Separation from Active Duty), which should have been issued when he separated from active duty, not years later as the one he had on his campaign website appears to have been.
Section I - Information needed to locate records
5. Service: Past and Present
a. Active Service
b. Reserve Service
c. National Guard
hmmmm...I don't know...it looks to me to be a slight of hand/loophole. You could be right - it just seems dubious to me.