Peter van Inwagen famously rejected the PSR due to his argument that it implied necessitarianism: Take the conjunct C of all contingent facts. Being contingent itself, the PSR demands an explanation F. F must be necessary. But if F is necessary and sufficiently explains C, then C is itself necessary, and hence no contingent facts exist. Because contingent facts do exist, the PSR is false.
But what if we maintain that an explanation for a fact F need only necessitate F's possibility, and consider the (alleged) true indeterminacy we find in quantum mechanics. For example, suppose the contingent fact that needs explained is C : "the electron was found in position x.", and our explanation of C is F: "A quantum experiment was conducted which entailed a probability of the electron being found in position x."
This would be an explanation which does not entail or necessitate C. Does this pose a legitimate challenge to van Inwagen's argument?