I would argue the opposite. This is a positive discovery for evolution. That the appendix has a function makes more sense than being just being detrimental to health.

Evolution would select out useless body parts unless a sudden change in environment/diet is observed which makes the body part useless/redundant. Such as the rise of human civilisation.

But only a god/gods would create an organ that is useless and has been useless for many many generations of our ancestors. This discounts a sudden change in environment as an explanation, since it should only affect the first few generations.