How can I get dad to move without having the house condemned?

Try calling Social Services and see if they can do a welfare check on him. That should get things moving. You are right to worry about him. People have a right to make their own decsions, if they are sound of mind, but this does not sound like a healthy choice. A third party may be needed to intervene for his safety.
Carol

Carol is right. There are many circumstances that are beyond the control of family or other loved ones. Frankly, I'm surprised more families do not take advantage of what in Florida we call Adult Protective Services.

As a unit of our Department of Children and Families, trained caseworkers are sent to the home to assess and evaluate the health and safety of an elder. I have had cases where siblings were squabbling to such an extent that mom was being neglected and placed in danger. You wouldn't believe how quickly everyone started singing a different tune once the "authorities" were involved.

For those that are alone, Adult Protective Services will make sure that there utilities, food, and medical care available or move the elder to another venue if required.