It is pretty silly. Even the cops where I live think so. If you are about to be deployed and get pulled over drunk, just show them your orders. They will escort you home and thank you for your service in most cases. I've seen it a number times before friends got deployed and were under 21. I can't speak for how they handle it Knoxville though.
We, as a nation, went through all of this in thhe late '60s and '70s. Old enough to serve, old enough to drink; so WE DID LOWER THE DRINKING AGE TO 18. (In Tennessee, after I was already 21.)
The result was highway carnage, and the 21 limit was reinstated, after Congress ruled states would lose highway dollars for not raising them back up.
It's a shame the US ever had drinking laws any different than Europe, where even children are served watered down wine by their parents at the dinner table, learn their own individual consumption limits and responsible drinking at home before they ever get behind a wheel.
Now laws vary by state. But in Tennessee it is illegal even for parents to serve alcohol to their under 21 children, even in their own home, to acclimate them to alcohol.
Result is a lot of craziness happens. Had we reasonable laws on the books for decades, this would have been a non-issue, except for the disturbing the peace. And that is real and understandable. As I said before, I hosted a few parties that got out of hand and was the one who had to answer the door when the cops knocked. My solution was to tell them I'd unplug the stereo and announce the parties over, not just turn it down or off, and I'd put on a pot of coffee and not let anyone leave til sober. Never had a problem, except been there, done that, and had to wear a tee shirt covered in her puke while I stood a buddys date in the shower to get her puke off both of us.
And why was that? Because in the US, especially states with laws like Tennessee's, parents can't teach their children how to drink, and most kids don't really start 'til they're out the house, they are still finding their limits in the worst possible settings.
I bet Yacob is a-frickin-mazed!