I wonder if in certain cases, just canceling and refunding the passengers is cheaper than providing hotels and/or arranging a bus bridge on short notice in a place where there aren't many buses or hotels available.You'd almost certainly keep the room. It wouldn't be returning as 3, 3 was annulled. So anyone booked on 3 that might have "your" room wouldn't be boarded.
My guess is since they didn't offer alternate transportation and your trip was effectively cancelled, you would be fully refunded.
As far as Amtrak goes, refunding all passengers, as they would have to do, would probably be more expensive than providing a bus bridge. For a bus bridge, coach passengers would be owed nothing. Sleeper passengers would be owed a partial refund of their accommodation charge for the missed segment, and they'd throw in a voucher and some AGR points for inconvenience if you pushed it. Cancelling and returning passengers to their point of origin feels penny wise and pound foolish to me.
If this is starting to be regular policy, that's concerning and is something the RPA should be making a stink about with members of Congress, especially since the 2025 Amtrak appropriation is now working its way through..