That sucks, but I don't think it was intentional. Sega CD and Saturn cases are NOTORIOUS for easily breaking.
...which is why he should have packed it very securely in a box. Heck, I won't even ship a disk in its jewel case because I've had too many arrive to me rattling around, I always put the disks in one of those envelopes Gamestop gives me when I buy something used & put that on top of the jewel case. Then put it tons of padding (bubble wrap, paper, etc.). THEN to make sure it's well packaged I close the box & shake it to see if it moves around - if it does, more padding. I don't understand people who won't package things securely.
It's not just individuals tho - I received my Conception II from Best Buy today, also in a bubble mailer. So who wants to guess what happened to the *cardboard box* the game is in during shipping? If you guessed "crushed flat", you win! And I lose! It's going back to BB tomorrow - I called GS, they have one in store that they're holding for me. I'll pay more for it, but at least it won't be damaged.