First of all I condemn all kinds of terrorism, regardless of the perpetrator. But let's not kid ourselves into believing that there is only one side doing it. The "Jewish terrorism" that the authors warn of already exists. Just this week and in the area there was the "pricetag operation" (read: arson) in response to the evacuation of a settlement and also there was vandalsim of Palestinian trees which resulted in 10 wounded Palestinians. Those kinds of actions are racially motivated and are intended to spread fear and to cause harm. You don't think they are provoking Palestinians to respond with their own extremist actions?
Israeli teen lightly wounded from stone throwing in West Bank settlement of Kiryat Arba (Haaretz)
from the article: Settlement attack could trigger terrorism by Jewish extremists