I dont see why it would make a difference as long as the container was cleaned before using it. A lot of people here use the superpet dusting house for their chinchillas and that isnt a very "open" container either. I dont think chins breath when they dust either. I think they roll stop for a bit to breath then roll again. Thats what mine seems to do.
I'd question that story a little more as you dont know what type of container it actually was, what dust they were using, or the chin's health at that time. If they didnt properly go assess the death with necropsy, for all you know the chin could have died from sudden heart failure.