How do we know they don’t have nukes? Because Israel hasn’t been hit, the second they get their evil paws on one they will use it within 10 minutes.
You got that right!
I doubt they would attack Israel with such weapons, for the simple fact that Jerusalem is the third holiest site in Islam after Mecca and Medina. Furthermore, there is a nation called the 'Great Satan' that is a bigger issue for most jihadis.
As for this threat, it is most probably not real. However, assume they are in possession of one device (most probably radiological) that is in place. It detonates. That just made the remaining 159 (even if they do not exist) very credible, and that would tie up a lot of resources as well as spread a lot of fear. I remember being in Oklahoma during the DC sniper days, and seeing people gassing their cars while bobbing and weaving ....all the way in Oklahoma. I believe one radiological device going off, even a weak one that is basically some mid-to-high power explosive core with some weak-radiological material that doesn't even kill one person, would make the threat of more attacks rise significantly.