This is bullshit from the religious Jews. They are acting like Jews die out, because of interfaith marriage.
Truth is that most Jews are secular and them kvetching about "dying out" because of intermarriage is like claiming that Europeans die out, because of church going rates or their religiosity.
The thing is that Jews don't even mix and create "half-jews". Jewish culture exists in such a way that even someone with minor jewish ancestry feels obligated to act like a total asshole on behalf of his jewish ancestry and genetics. It's like a mind virus. "Oh, I am a Jew? Awesome, I get to have pride in jewish culture, jewish privilege and social and moral protection? And real life protection like being able to migrate to Israel, if I get discovered as a pedophile? Now let's tell white people that it's important for their children to learn that if they feel depressed and feels like puberty is creating anxiety, that they need to cut their dick off and take female hormones."