You asserted, "No. Radioactive decay is spontaneous and uncaused ..." Perhaps you are confusing a reductionist perspective regarding symmetry breaking with a concept of emergent phenomena ... the Pauli exclusion principle may be applied to explain decay even though it is not possible to show the causality in action of decay. Tortoise is fond of pointing out (wisely) something to the effect of random is not to be confused with 'uncaused'. That you cannot define the specific cause for decay on the scale of a single atom should not be misinterpreted to signify no causality. With the development of the concept of emergence, we find that indeed all events in our universe of spacetime and all its permutations have a cause, though some causes are unknowable in current research. It is simple enough to prove to yourself: if an event happens in this universe then it is somehow involved with entropy and thus exists under 'causality' not beyond causality.
No, there is no material cause for the decay - it is not dependent on any prior event or state, and hence there is no definable cause. This is not a misinterpretation.
The universe is how it is, regardless of how inconvenient to our philosophical constructs that may be.
There is, nevertheless, at least one event or entity that has no cause or precedent. The necessity for causation is negated by the observation of existence.