It's better than nothing, but most covers do not protect against bending or torsion well. The best solution is to avoid any kind of force in the first place.
Same way noise dampening mats in a PC case don't work nearly as well as ... using silent components that don't produce any noise in the first place.
People who know how to swim are much more likely to drown than people who don't, because the latter group avoids water in the first place.
If your bag is bursting at the seams and likely to be squashed or sat on while traveling, it's not a good place for a reader no matter what the case it's in.
If you have to put it in a bag, probably best if it had a dedicated compartment for the reader and no bulges in odd places that could bend/torque/apply force to it. So if you put it in a computer case it probably should not share room with the laptops PSU brick.
