That is true, they can boycott, I guess, but in the end if the rooms really are built, they will be filled, no matter how willing or unwilling the occupants may be. One way, though, is for the students agree among themselves to limit 3-person rooms to a max of 2 people, with whoever is last sacrificing a chance to stay on campus as a message to the administration (and a chance for the 2 staying there to save some money as well.)
I saw the interview as well, and yeah I think I had more space in my bunk

Not sure about listening to complaints from foreign students more than those from local students, I think we're treated equally in that respect at least by the NUS admin.