I would at least expect them to be able to demonstrate their magic rock and let me try it out on various materials.

If they had a rock that they claimed could pick up copper but not brass, based on only one experiment, but the rock now doesn't work if any scientists are watching, I'd be disinclined to privilege their hypothesis of the rock's magic properties.

Nobody is outlawing the evidence. I'm saying the evidence is unconvincing, and far short of what is needed to support an extraordinary claim such as precognition. It is for example much less rigorous than the evidence there was for another causality-violating hypothesis: FTL neutrinos. That turned out to be due to an equipment defect. Many were disappointed but nobody was surprised. Same reference class if you ask me.