For YEARS I had a pet store that specialized in reptiles. The only time we kept ball pythons individually was when we were down to one. They ate. The pooped. They were happy, friendly, well adjusted snakes.

Over the years I've kept them in small groups and as individuals. I've never really seen a difference in the snakes kept either way.

If they're kept properly as far as environment and food availability, I don't think it makes a bit of difference if they're alone or with friends.