The Mossad part is a very silly element of the text. Many organizations have to defend against US intelligence, Israeli intelligence etc., and I'm sure, that they, with the exception of some very terrible countries with a lot of incompetence or full of disloyal people likely to become infiltrators, are quite successful.
Actual security is possible even against the most powerful and determined adversaries, and it's possible even for you.
I think, a lot of people imagine these people as very capable, and they think of things like those pagers etc., but when I think of them I think of the Lillehammer affair and a bunch of other similarly silly business, so I'm much less impressed with them, feeling that they're basically silly people.
There's so many cock-ups etc. that you can read about Wikipedia that I don't understand why people hold these people highly and imagine them to be so able. They simply aren't.
Actual security is possible even against the most powerful and determined adversaries, and it's possible even for you.