There's a non-zero risk of contamination with any approach. Whether from the ice maker or the tap, you can find black mold. How often do you remove and clean the aerator on your kitchen faucet? I've topped extract batches from the faucet, from the ice maker, from "beverage grade" ice, and ice made in frozen storage containers. I never got an infection, but maybe I just got lucky? I will say, I think if any of the approaches were particularly stupid, my wife, brew partner, and professional microbiologist would have said so. She is generally very quick to point out when she thinks I'm doing something stupid.