Tillikum Not Getting Rewarded

One thing that always gets me about Dawn's death was the mistake that may have triggered it. One of the trainers explained that Tillikum did a perfect pectoral wave, but he missed the cue to come back and get food. So he went all the way around the pool AGAIN, but then they did a 3-second neutral as if to say "No, you didn't do a good job." Was it SO HARD to realize that he deserved to be rewarded? And the fact that they were running out of food in the bucket...would it have been SO HARD to just get more? I think Tillikum snapped and decided to "show" Dawn...but unfortunately it ended up in her death.