I think I read in one of the trade magazines that Sam, not knowing that Bill was lactose intolerant, had given Bill some milk to drink about 15 minutes prior to the whole Crebain incident. So when they came swooping in Bill was, thankfully, "off-screen." It was a good thing to, because our Fellowship would not have gotten Bill hidden in time and, as they say, the jig would have been up.
-Kevin