From what I have heard from friends and read here on Ehell, I have serious doubts that living in a college dorm is the only (or even the best) way to become an independent adult. It may be great for some, ok for others and not work at all for some. The friends have expressed their opinion and should now shut up about it.
However, at this point, I do not think it is as easy as saying "we are the parents, we have decided", as previous posters have said. I assume that a college kid is over 18 and, therefore, can make his own choice, including getting massive amounts of debt. Making it all the parents' decision would seem to indicate that your son isn't being allowed to function as an adult, which would be fuel for the comments. Something as simple as "We have all talked about it and Son is comfortable with his decision" may be better.