Well, a short while later I bet B5 was kicking himself:
How amazingly useful is that?
Never mind that someone with the ability to alter the visible spectrum would not actually be able to effect the actual radiation emitted by Krptonite. Forget the terrible science.
How many times has Superboy been jobbed due to Green K?
Now imagine that you reject someone who has the power to alter Kryptonite.
Man, I bet Superboy kicked someone’s butt later.