I think the power that was shown in the episode depends on the original user. Otherwise, Boruto also has purple lightning according to his character profile. I don't think it makes sense that SP chose purple lightning in this case to be honest, but if nothing else. It might imply that Boruto's purple lightning is weaker than the one he used via that techonolgy.
Also, it's not the fact that it's "purple lightning" it's the fact that it's electrecity. Had Mitsuki's jutsu been strong enough, then his lightning snake would have done it as well, but it's not.