@sbjdorlo I believe most coops are full time and most are paid-and some are very well paid.
I think the best way to look at this is that while on coop the student may be able to pay their living expenses if they live in Boston which is a very very expensive place to live in.
The coops are everything they have claimed to be at least from my direct experience.
I would have your son contact the department I am sure they will make a connection for him!