The way I see it, Goku wouldn't be a "bad" guy more or less like a guardian considering that he aspires to do good. But in a PvP like setting he would eviscerate any guardian. The whole premise is that Goku would partake in the Destiny universe and be a part of it and so would obtain the base mechanics guardians have in the first place in order to set a middle ground. The debate here comes from whether other abilities such characters possess would outweighs another's.