The first is that the slow progression from simple to sentient life will often be stopped in its evolutionary tracks. Intelligence on Earth was slow in coming. It has been 3.6 billion years since life arose on our planet, and 600m years since the Cambrian explosion of complex, multicellular creatures. But one didn't happen here and Earth is not likely to be an astronomical rarity. The chain of life has snaked unbroken through every disaster for over 3.5 billion years.
Life is durable.
But there is no reason to think that large planets able to deflect lethal rubble from the cradles of life are scarce. Your second argument is that aliens should be in the neighbourhood driven to colonisation by imploding stars but they are not. This argument, as you know, dates from a remark by the physicist Enrico Fermi in 1950. Indeed, it provoked a cottage industry of research intended to explain how aliens might be plentiful, but poor travellers. Many of these explanations are reasonable.