You are right to say that journalists who work in totalitarian, or failed states or entities, fear that if they report the truth, they might no longer be allowed to work there, or that they will be physically harmed. Much that was happening in Iraq under Saddam was not reported by some major newspapers for that very reason. Nevertheless, this call for boycott is without doubt motivated by the same extreme anti-Israeli sentiments that have fueled other similar adventures by various UK organizations.
Opposition leader Isaac Herzog calls on government to allow Syrian refugees into Israel (Haaretz)
from the article: Guardian editor condemns U.K. journalists' call to boycott Israel