I'm not actually a student at UW and never was, but here's my stab at an answer. (I think the students are all busy!)
Rush is held before school starts, so theoretically no one is moved in yet. Of course, if you're out of the area you need a place to stay, so they give anyone who wants one *very* temporary dorm rooms for the duration of rush. If you drop out, I'm not sure what their policy is on finding you a room.