I don't think it's really that bad, how they are keeping them.
If the snake is not a water dwelling snake, then it is not really a problem. It looks like the betta has it's own side, and the snake has one of it's own, I can see part of a dry land.
The only problem would be if the people were not careful about it, like making sure no accidents would happen.
Yea, that looks a bit too close, but maybe the snake doesn't actually try to eat the betta, they did say the betta attacked the snake, it probably thought it was food.