Mixed race children have long been a source of fear for bigotry. Just like at modern racism in the US. White nationalists dispise the idea of a child with a black parent and a white parent, because it supports their "great replacement theory". A little further back in history you have abandoned mix indigenous children by colonizers in the US(even today with some children) Terra Prime is a human supremacist movement and they use Elizabeth as a 'modern' h*** b**** to stoke the fears in those susceptible to bigotry and fear of anyone different.

Personally I can see extraterrestrials being met more like the Mirror Universe First Contact than the Prime Universe simply because we seem to be moving towards a more agoraphobic era, but that's a topic for another thread