An obvious rejoinder to this is that while a Boeing 747 could assemble itself naturally by chance, the fact that we don't see any 747's occurring naturally isn't evidence for their impossibility. Therefore doesn't your point about no sun-like stars going nova only carry weight if we assume that there is other intelligent life in the observable universe?

As a side note, I read somewhere that John von Neumann once had an epiphany in which he imagined that supernovas were the final acts of civilizations that had learned to harness the power of nuclear fusion. We could even imagine von Neumann probes being constructed with this purpose, destroying every star in their forward causal cone. You have to admit, it would be a funny old universe if it turned out that such a thing were possible!