Katrina != 9/11.
In September of 2001, Amtrak was the only game in town for a few days.
Amtrak is just as necessary as airports and roads.
The Louis Armstrong Airport was shut for some days afterwards as well due to storm damage.
But I fear that the "insurance policy" is mostly against another big terrorist attack. (Weather disaster would be localized.) An oil price crisis is also quite possible. One or two atom bombs on ports in the Persian Gulf could double gasoline prices within hours and linger for weeks and months or years.
We had an economic crisis just 7 years ago that some of thought needed more of a response than we got.
And not to mention melting ice caps and stuff.
In a disaster, I could imagine Congress saying, "How much money do you need to do it?" -- while ordering Amtrak to double or triple capacity in a very short time frame.
As usual equipment would be the choke point at first, but we now have three factories that can build cars for Amtrak. Then we'd need lots more tracks. Every plan for new or more corridor service or even new or restored LD trains would be dusted off. I hope we have more stuff close to shovel ready than last time. LOL. In that disaster scenario, the national system is the foundation, and building a new system from scratch would be very, very costly in money and time.
I'm not sure that "disaster insurance" is worth $600 million a year, but that figure is declining, and the insurance would be worth something, say $100 million. Then we're down to quibbling about spending a mere half a Billion, an amount the Pentagon probably blew thru while I was writing this comment!