I can see how you can read that comment as a dig at the DLI, but that wasn't my intent.
I've had many experiences over the years with both Monterey and DLI, and one thing you neglected to mention was that the average "frat boy" at DLI is in his forties, about 15 years older than the average at Monterey. While the merry Monterey kids tend to be fresh from the trenches at some campus political activist club, the average DLI student has spent those extra fifteen or so years on the ground, in military or diplomatic postings, dealing with life and death issues deep within other cultures. If they seem grimmer than you, it's quite possible that they have lost some of your frat boy illusions during those fifteen years off campus.