That would imply that it would only be worth trying to prepare for hurricanes, because work there would improve public reception, while terrorist attacks would go badly no matter what you did.
But FEMA can't prevent attacks, they only show up after something happens so there’a no incentive for the agency to focus on terrorism from that angle.
As a side note, I wonder if there's also a bias that human minds are more easily controlled than forces of nature. That may also come into play here.