The steam before using dry heat is real. Once wood has been brought down to really low MC by artificial means its propensity to be bent by steam is greatly reduced. Thats why chairmakers, and other craftsmen that need tight radius, steam bent curves always use air dried wood, as kiln dried wood is nowhere near as elastic. Every book on steam bending or wood usage I have read says the same message.
Whether this is due to having lower MC, or if its due to permanent structural change, I don't know.
If its just due to MC, then rehydrating the wood by soaking for a couple of days might be an option.