He must've done 'extensive research' during the last 10 days. Or maybe, though highly unlikely, his and his family's life were threatened, he was told he would be fired and most importantly he was made to understand that his work put 'future of jews' at risk. Another job well done.
In Bahrain, 2 police officers killed, 6 wounded in bombing (AP)
from the article: MKs demand the author of blood libel book be prosecuted