Would they not fall into the "Believe the OT" first?
I doubt that most of these Jews were ever raised with the Torah. Many were raised in liberal, secular families and their very first experience with G-d and the Bible was via chr*stianity. Orthodox Jews hardly ever are seduced by chr*stianity.
At any rate, the fact that Jews have apostasized does not negate the Torah. Jews have been apostasizing to false religions since before chr*stianity existed.
I'm glad 12 were...