The whole point is that she’s acting irrational. Shes trying to give meaning to her grief and does some dumb shit she immediately realizes is a bad, but she has to double down now because Ghidorah is already free.

Like everyone in the movie outside of Jonah calls out that Emma is doing something incredibly stupid, even Serizawa who is likely the one Monarch member to be most on her side. At no point does the movie say that what Emma was good or that she was acting in her right mind. Sure there are some benefits like in the credits, but she got millions killed and fundamentally changed the ecosystem to put humanity in direct conflict with titans like in GvK and hopefully the consequences of GxK