So that it splits has a reason; when it splits doesn't, or it wouldn't be random. That you can average out random events to get some sort of general sense doesn't mean that there's a reason.
O.
In each case of indeterminancy we sort out whether something is indeterminant because we don’t have the Knowledge, because we can’t have the knowledge vis Heisenberg or is truly random.
I believe philosophers introduce what are known as demons, entities imbued with the knowledge we lack.
Are you saying that in the case of radioactive decay, such a demon would not know and subsequently we don’t know because we don’t know?