This is an interesting question, although I think "training the enemy" is hardly the correct description. Generally speaking, I have a really hard time with the idea of limiting who can get athletic money in college. Whether the argument is that we're hurting the development of US Olympians or just US athletes in general, I think we'd lose something if foreign athletes weren't able to compete in our collegiate system.
E.g., consider Wesley Korir. For those who don't know, Wesley is a Kenyan who competed for UofL and has gone on to win the Boston Marathon. I think Wesley is one of those guys who's ultimately made a lot of people better off, just for having known him. If you go back to the late 70s, you'll find WKU led by Brits like Nick Rose, Dave Long, Swag Hartel and others. Those guys have obviously added a lot to this country, the least of which being that at least several stayed here. Swag has one of the best running shoe stores in the State, hires lots of local athletes and sponsors plenty of local meets. Dave helped run one of the local clubs in Louisville for years, and has been a great resource for many people when it comes to running. His kids both ran in HS and later in college, and now he's got a nephew coming to the US to run, I believe next year. These guys have given back significantly, and we are obviously better off for having brought them into our system.
On the other hand, I do understand the concern as well. I've seen programs over the years who bring in plenty of internationals, rarely developing any of the few US runners who come their way. The foreign athletes arrive in large numbers, they compete and do well - in some cases while their US teammates seemingly languish - and then those athletes go back home when it's all over. In these situations, I can see how people would disapprove or call for "America first", and I understand how people can even claim that foreign athletes can make some programs look a lot better than they would otherwise be, or perhaps even give a somewhat false impression of the quality of the program. I'm not sure that these are valid concerns, but like I said, I can see how people would think that.
The bottom line is that coaches are hired to win, and if the best way to do that is by bringing in foreign athletes, you really can't fault college coaches for following their incentives.
Very few collegiates go right into the Olympics. if you are going to complain about something I think a bigger argument would be the scholarships they take away from US students. I have no problem with either but I think more HS students work hard at athletics to give them more opportunities at making college affordable.
...I am going to add to the fire from an athlete perspective... Colleges have been recruiting foreign athletes for years… especially for long distances. Back in the late 80s I was a walk-on athlete… one of the reasons I decided to take running seriously was because I was tired of hearing about the foreign athletes in my college. In a sense the fact that those athletes were there pushed me to become even better. On the other hand several of the coaches in my college knew I could run but none came to recruit me (no scholarship). They invited me to practice with the team when I was a freshman… but it wasn’t until I took it serious (sophomore year) that I got my scholarship. I can see why colleges don't recruit "potential" or "talent"... but if we want to make running (long distance) important again in this country... they need to take their chances.
I think coaches do recruit potential in that they're certainly always looking for a diamond in the rough, but it's obviously more difficult to identify those diamonds, and it's tough to know how a kid will respond to collegiate training. In that sense, diamonds in the rough would seem to be a riskier choice than established runners. E.g., my guess is that proven commodity like a Footlocker kid will still get more attention than a kid who runs well on let's say lower mileage, which gives the impression that this diamond may potentially be as good as the Footlocker kid in the long run. Although the potential may be there, the diamond may still be a bigger risk than the proven commodity, because a bird in hand is always going to be worth two in the bush.