Exactly pal, the king was surriounded by Yogis and priests around him. Althought the king tried to distance him from those knowledge with other pleasures, the boy was exposed to spiritualism which might not have been the intent. There were priests, Yogis and hinduism rite in front of the boy; he made a choice..? You know how people make choice ?..its when they are able and willing. He had everything a prince would ask, he also was exposed that there were other ways to view life and he made a choice. The knowledge or information was there, he learnt it as a hindu prince. Once he saw other things as old age , death he confirmed and moved on. Just imagine a hindu prince would not be taught about hinduism - that is nonsense in itself. He did not just see a dead person , got scared and become a sadhu. The knowlede was there and he mastered it. The point is,he was exposed to spiritualism of hinduism just by the fact that he was a son of hindu King and the king in those days would surround themselves with religious figures for various purposes. He found what was mentioned in hinduism not other way around.