Chances are, this iPad had prior damage (possibly unnoticed).
Apple has sold something like 350 million iPads. The number of screen "explosions" due to altitude issues? Close to zero.
Also the 10,000 ft operating limit has been standard for virtually all consumer computing devices (laptops, tablets, even iPods, etc.) That's partly because consumer-grade hard drives may fail if operated above this altitude. Most devices with modern solid state storage will work well above this altitude but the manufacturer isn't obligated to guarantee it.