He has good arguments (except for one) but history has mostly shown that it's not wise to say something can never happen.

Now for what I feel was one of his bad arguments:

"None of today's military aircraft are up to the job of intercepting it, and indeed, active radar can't even track it effectively—for that, you'd need something on the order of a cold war ballistic missile warning radar system, designed to provide advance notice of an ICBM strike."

In one sentence he outlines both the problem and the solution. Doesn't the west already have missile defense systems?