I don't like to use ANY sort of hide that I can't pick up and get an animal out of without causing trauma to the animal. I don't think there's anything inherently dangerous in using something like a paper towel tube, but you won't ever be able to easily get a snake out of one, and if you HAVE to get the snake out, you'll cause a lot of stress in the process and could possibly risk injury. And if you ever "graduated" from paper towel tubes to something like a pvc pipe, you could find yourself completely unable to extract the snake without a real risk of injury. At least with the paper tube, you can tear them away.
All my hides are things that I can lift straight up to expose the snake underneath, although sometimes they'll still try to "stick" to the insides of their cave. LOL