Its not the geatest tube( emovie) but its far from the worst. It is solid. it would take some special act to do that to it.
I just assume USPS dumps the tube with a bunch of other packages and it won't survive transit unless you use a strong tube. I use the "can the tube be squeezed with one hand?" test. If it can't, it should have survived transit and you shouldn't blame the seller.
I did your test. I cant squeeze it with two hands. I have to stand on it to get it to move. I dont know what they did to it but it was a determined effort. They must really hate tubes.
You'll have to fight USPS on this one, then, if it's worth it.