Wouldn't be too sure about that...
With enough radionuclides in the planet there would be enough heat-flow to keep a deep hydrogen atmosphere from condensing out - and that would create a nice greenhouse effect with a surface pressure 100-1000 bar and liquid water or ammonia/water conditions. An early ejected planet should retain a primary atmosphere of H/He dragged out of the protoplanetary nebula as it formed. Mini-Neptunes would also retain liquid oceans, though they might be too deep for life as we know it.