Sure, maybe! My point is that they had a lot more pertinent details at hand to make a risk assessment with. How was the bomb warning made? The crew quite rightly reported it to ATC. After that it may well have been that further investigation by all (El Al) parties involved concluded that it was highly likely to be a hoax and the decision was made to continue. The bottom line is that we just don't know. I am however convinced that they knew exactly what they were doing.