The chronic stress, frustration and physical inactivity will have suppressed Tilikum's immune system. Few killer whales have been able to survive in captivity as long as he and it's a great wonder that Tilli lived as long as he did.
SeaWorld will make an exaggerated claim that Tilikum had lived the "average" lifespan for killer whales in the wild. However, Tilikum's longevity in captivity is proof that he wasn't an average killer whale and it's known that males can live to an estimated 60 years of age in the wild.
Would he still be a healthy, vital and thriving animal if he was never taken from his natural environment? There's no doubt in my mind that he would.
No amount of SeaWorld's "enrichment" and care, can replicate life in the wild where each day, each moment, is different from the one before.
Life in captivity stole Tilikum's health and warped his mind.
He was no ambassador for his species, no willing subject of research. For SeaWorld, Tilikum was a showpiece that attracted dollars to the front gate. He was masturbated for his off-spring to propagate magnificent animals that, through successive generations of captivity, have lost much of their natural abilities and vitality.