I don't think so. I think what was meant was what was literally said: that 88% of youth qualified for the military are in college.

66% of youth are not qualified for the military or college, leaving a remainder of 34% that are qualified for the military, college, or both.

X% of youth qualified for college but not the military (qualified for college here meaning attending college, I think.), leaving (34-X)%.

Of those, 88% attend college .88(34-X)%,

leaving .12(34-X)% eligible for recruitment. Which ends up a successful recruiting number like 63.5K, which is from one of the references.

I could be wrong, but it could make sense.

But also, 2/3rds of 34% also leaves a remainder of about 12% (which is a bit coincidental), so maybe what was meant to be said was that only 12% of (all American youth) are (qualified) and not (in college), rather than only 12% of (the qualified) are not (in college.)