That is selfish. Just because they aren't eating each other doesn't mean they get along. Other snakes aren't part of a corn's or bull's diet in nature, that's true. But when they are confined in the same enclosure together especially after feeding, they can accidentally mistake another for food because they can still smell it. I found an example on Youtube.
http://www.youtube.com/watch?v=vaRYt9oitG4
It's frustrating how irresponsible people are with snakes. Even if they are eating and showing no sign of illness, stress is still affecting them and shortening their life. If an animal is solitary by nature, the best thing you can do for it in captivity is to keep it that way. It's for a reason.