Actually one of the actors, Dror Keren, has already announced that he is withdrawing his name from the boycott letter. Its possible that the wording was changed after they signed. In any case whatever the reason all of the actors involved (only a part of the signatories) can be replaced for specific performances.
Islamist militants attack African Union base in southern Somalia (Reuters)
from the article: 53 theater figures vow not to perform in settlements