Equating your snake to how mammals, and humans in particular act, is not terribly useful, IMO. They certainly don't need the interaction mammals need, and they do not require the exercise mammals require. They have numerous psychological and biological differences in their requirements.
You're assuming snakes find swimming enjoyable rather than stressful. Humans enjoy going to the beach and swimming. Do BP's enjoy being stuffed in a styrofoam container and forced to swim around for 40 mins? I've never seen anything to indicate they enjoy that. I've seen far more evidence to indicate that something like that will stress them out, further reducing their chances of eating in the near future.
If you're trying to get your snake to feed again, your snake is far better off being left alone for a week in relative peace and quiet than he is being dropped in a container of water and forced to swim around for 40 mins a day like he's a dog, hamster, or horse in need of exercise.