French Jews must move to Israel if they are religious Jews because it's an essential commandment to live in the Holy land, especially at a time when it is easy to move and settle. Exceptions to this rule are very restrictive.
But to say that Jews should move to Israel to be safe is questionable on at least two grounds. First, the primary motive is not to be safe. In other words, religious Jews must move to Israel whether Israel is a safe place or not. Second, Israel is not exactly a safe place for religious Jews. The latter are faced with two sources of danger there : the Arabs and some of the secular Jews. Jews don't have their homes destroyed by the authorities in France or in America. Jews don't get stoned or shot at on a regular basis in France or in America.