Yes, draining to the floor is part of the 2021 IRC. See codes.iccsafe.org/content/IRC2021P2/chapter-28-water-heaters#IRC2021P2_Pt07_Ch28_SecP2804.6.1. This is code for the discharge pipe of the relief valve, meaning that the floor should only receive this water in an exceptional case, and the code also calls for the termination point of the discharge pipe to be seen quickly ("readily observable"). I am not aware of the discussion or thinking that resulted in the code, to be clear.

@@porkysbiz it just seems like a terrible idea to relive the tank of scalding hot water onto the floor

@@tristangriswell2034 I hadn't considered that; I see your point