Goku does have light, example is during the begging of the Buu saga while chasing after Gohan's stolen energy they face a villain who drains the ssj power by absorbing the "light" it createz. Ergo Goku has "light"
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Thats the light of ki, but not the ontological light that exists within the destiny universe.
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But Goku doesn't really know how to use "light" as a weapon