The argument never establishes a high probability of a disastrous event. The author’s prescription would be reasonable if that risk had been established, but the past average doesn’t support a prediction of the next strike’s timing.

The argument does the opposite of this. It supports its prediction of the next strike’s timing by citing the fact that a strike has not occurred in nearly 100 million years.

This describes how the argument misunderstands what the past average indicates. Just because there’s been a historic average of 100 million years between strikes does not mean that the next strike will occur about 100 million years after the previous one.

The possible effects of a future strike are irrelevant since the argument fails to establish that there will even be a strike.

The argument does not claim that large strikes can be deterred. It claims that the high probability of a large strike in the near future warrants funding to determine whether or not Earth is protected. The problem is that the high probability of a large strike isn’t established.