The bolded part kind of specific regarding her targeting the kid. However, the last part really shows that she really cherished life and would have completely sold out on revenge for her village to stay on as on of Dani's girls by saving Drogo.Here are a few lines from the book I found on a site that calls Mirri a hero for killing Drogo and the baby because it saved the lives of thousands of innocent people that would have suffered their wrath and destruction.
The bolded part is key.
As I said, without a POV or Martin specifically saying, it isn't far fetched to see how people could see Mirri and her actions differently. Preslove is just a tool.
He'd probably argue that jon is actually baby aegon and gregor killed a replacement.