Yeah, mate.... I'd not expect that from a good size capa either... These are rarely kept even in public aquaria, and I think that even if someone at Shedd, miraculously, had a firsthand experience and knowledge of capapretum, things like these are much more often unpredictable than not. There are so-o-o-o many factors that affect the intro of a new fish.
Sure, I agree, there are tendencies and knowing that a fish is skittish and flighty makes one adjust their procedures, but then life happens and often that skittish fish survives just fine while a non-skittish one may perish. Life's often a gamble and 50-50 happens left and right.
You and Shedd took a gamble and lost. If you took 20 gambles, you'd win 10 or more, I'd think. So, cheer up. In the words of Red Green "Keep your stick on the ice. We are all in this together". I once lost ~300 lbs of large fish in one shot, some rare - most of my prized collection. You cry, pick up the pieces, learn, and move on.