I don't get it.
It the malicious circuity has to be triggered externally and it's unknown when it'll be used, that means that either:
(1) hackers have to get into a network linked to the hardware or
(2) there has to be an external radio signal which can disable the hardware or
(3) The hardware (radar in this case) doesn't validate it's input well enough and is open to buffer overflows/ bad execution based on invalid input.
From what I've read, the Israelis exploited (3) in order to disable the syrians radar systems.
It seems to me that the syrians bought just plain crappy radar systems and then never bothered to test or "fuzz" them.
However, the article seems to be going crazy over (2). However, a simple faraday cage should be good enough to defeat that kind of attack.
It'll create a barrier between the inside of the container and the outside. No EM radiation goes in, no EM radiation goes out.
Any kind of circuity triggered by EM would be defeated. And by definition, any circuity triggered by time is useless because it's impossible to determine when in the future, it'll be required.
And (1) is easily defended against by not connecting your critical defense hardware to any network of any kind. Or by using 3rd party firewalls which have not been made in China/Russia/Iran...
So this is much todo about nothing IMHO.