According to the article,Youssef contributed to the prevention of dozens of suicide bombings and assassination attempts on Israeli figures. Those suicide bombers might have caused the lives of babies,children,elderly people. But as these lives saved were those of Israelis (i.e.Jews),the usual Israel-bashers (yes,those who whin when a Palestinian baby is placed by his/her parents in the middle of a battle to be killed by the fire so the parents can accuse "the cruel Israel") call him a traitor.
Russia says kills six suspected militants in North Caucasus (Reuters)
from the article: Haaretz exclusive: Hamas founder's son worked for Shin Bet for years