This avoids the question. If it helps, try to construct a version of this in the least convenient possible world. For example, one obvious thing to do would be that something about theory X means the plant can only be turned on at a certain celestial conjunction (yes, this is silly but it gets the point across. That's why it is a least convenient world) and otherwise would need to wait a thousand years.

One can vary the situation. For example, it might be that under theory X, medicine A will save a terminally ill cancer patient, and under theory Y, medicine B will save them. And A and B together will kill the patient according to both theories.