Bigots become xenophiles. Inquisitors become converts to the beliefs of those they had tortured, then leave belief behind entirely. The symbol, properly used, can move any awareness anywhere, even to an opposite extreme. The Leaping Dolphin allows one to leap across vast cultural and phyletic distance. The experiences are not remembered because of the vast phyletic distance.
Dolphins have a very alien cognition and perception, a different memory mechanism.
Those humans must have used the Leaping Dolphin symbol to make the shift. There seems to be more shapeshifting going on than there is enlightenment. When humans shift to Dolphin form when they sleep, they are already in spirit form. They are not truly human, they are far removed from their conscious, daily awareness. When the spirit body materializes on a dolphin starship, the physical human body dematerializes.