As I said upthread, I think there is a lot to be said for solidifying a language before you get to college. When I came back to visit my high school French teachers after my time in France they were amazed. They’d basically written me off as hopeless. I got paraded around all the classes as an example of what a little immersion could do. 
Chiming in again to add that my daughter’s experience in this program was that mastery of the language was in no way required before participation. She had 5 years of Spanish before attending and also felt like she hadn’t learned anything. That was true of most of the other kids in the program. By the end, most of them felt fairly fluent. Personally, I think the potential pitfalls of joining the campus community in January/February are, for most participants in this program, greater than the abroad experience itself. Just my two cents. Good luck to your son wherever he chooses to attend! I’m not sure if you can pm me, since I am a new poster, but feel free if you are able.
To close the loop, my son has now had a chance to meet and talk with other students at the college who have done this program, as well as to meet the program’s resident director. All of this has assuaged his trepidation (which was mainly around his lack of facility with the language), and he has decided to accept this offer!
Good luck to your son @colfac92 - I’m sure it will be a terrific experience for him (and, as a parent, I’m pretty darn jealous)
Just to clarify - not jealous about being the parent of a kid going to France – jealous of the opportunity to live in Europe for a semester!