Well, first of all, that's not what he meant, so you can't say thgat he's right.

But as for the actual thing... No, I don't necessarily think so.
Of course there are exceptions, but most people who join the military have limited education and career opportunities, everybody knows that, so why should the guy have to apologize?
Perhaps they may have limited educational and career opportunities before they join the military, but that certinatly isn't the case after they join the military. It's literally advertised everywhere, after all - go to the military to get an education. I don't see how it is any different from, for an unequal exam, going to a community college so that you can go to a more prestigious college later on. Sure it may seem less prestigous for one to go through such a process, but it still works out in the end. The result is what you get out of your education, not what you qualify for.
Besides, the military has a ton of different applications, not just the regular old grunt soldier steotype. Engineering, health, security, computer science, etc. are all major examples of how people with no experience with true "military" stuff can still be heavily involved in the military.
Besides, you can't say that the major aspects of the military don't require smarts. Sure, shooting a gun doesn't require smarts, but military tactics and strategy sure do. There's a reason why generals are so few, after all - it requires smarts. More importantly - other than the issue of corruption, there is a very practical reason for why the military is seperate from the civilian government. And that is simply the issue of specialization - quite simply, the military is a lot more complex than the average joe thinks. Not every soldier is going to be a grunt, anyway. (And do you honestly think that someone who makes the military his/her career will stay a private forever?)
This is coming from a guy who (still) has a prejudice of the military filled with the ex-bullies and jocks of high school, and one who can absolutely call himself an elitist who thinks that science is superior to everything.

(I really should find that Onion article) It's because the military is an academic field (And absolutely not my speciality) - as well, many application from other fields are extremely important in the military.