Speaking from the art school perspective, CoH is an awesome game but it's also crazy old. 3D modelling has moved on a long way and the way you'd create assets for COH are quite unlike the way you'd create using current methods and software. Unless the student is aiming for a specific retro niche, COH models may not be a good use of time for building a portfolio.
But I would also discourage learners from working on anything for free. The attitude toward art and design students doing work for the sake of work experience is downright predatory at the moment. Not to say that Homecoming would behave this way, but it would compound the problem.