Answer

As for Ben-Gurion Airport, this is not a simple question, but it is commonly accepted to permit it, just as with security work in the army. Especially since these are people who are, in a sense, coerced transgressors (since many of them probably do not think one needs to keep the Sabbath). In the army you are obligated to serve, whereas here this is a job you choose, so there is room for the reasoning that it is preferable to avoid it. In any case, if this is your livelihood, in my opinion there is no obligation to give it up in order to avoid this. As for witness protection, at the moment they are in a danger that cannot be prevented. The fact that it happened because of their own wrongdoing in the past does not matter. At Ben-Gurion Airport, the danger is due to Sabbath desecration that is being done now.