I wouldn't have a snake out on the floor for too long, no. But, some people like relaxing at the computer or television with a snake on their lap and as long as the snake tolerates handling well, I don't think this is an issue. As said above, your body will heat the snake, and I only do this with snakes that remain calm (they'll basically fall asleep or act close to it) and are eating consistently. I've watched entire movies with a snake on my lap without any bad consequences.
If the room temperature got very low though, ambient temps should be taken into account. Some people don't heat their houses at all and live in areas where it gets quite chilly, and this would not be ideal for taking a snake out in. However, at 70 degrees for ambient I don't think you have a problem.