Since I had a similar experience recently, I can tell you not to expect much more than token compensation (7.500 points in my case). Even though you technically got walked upon arrival, the T&Cs for Marriott Ultimate Reservation Guarantee state that it only applies if the property you booked was actually open for business on the night(s) of your stay. Since Marriott can claim this wasn't the case and the Aloft was closed, the URG compensation doesn't apply.