Does it blow your mind because it seems ridiculous or because it is being seriously considered?
The whole thing, really. That such a thing would be considered a "disgrace" by some, that in someone's warped mind such actions might be viewed as requiring some type of retribution, etc.
I agree with you entirely. There should be no such idea, however, it is a realistic thing as I have heard stories of this type from close personal friends about relatives, especially involving inter-faith marriages.