I dont' think the container itself is too small, but I also wonder about the choice of hides. You want something you can lift off the snake. If the snake gets into a tube and you need to get it out for some reason, you could find yourself in trouble.
I tried using a paper-towel tube as a hide for our gopher snake when he was little...ended up having to tear the whole thing up to get him out. Don't know what I would have done if it had been heavy plastic.
EDIT: Looking at the pic again, it looks like the backs of those things screw on and off...which would allow you to get at the animal...still, if that's the case, it seems like it would cause way more stress and trouble than just a simple plastic "cave" you could lift up. (Said "cave" being a plant dish, small bowl, or whatever.)