The viscosity of hot water is much lower.

https://profmattstrassler.com/articles-and-posts/particle-physics-basics/how-the-higgs-field-works-with-math/

https://en.wikipedia.org/wiki/Curvature#Space

https://en.wikipedia.org/wiki/Manifold

https://en.wikipedia.org/wiki/Dimension

https://en.wikipedia.org/wiki/Curvature#Flat_space

Curvature is well defined for manifolds with any number of dimensions. “Flat” in this context means “zero curvature”, not “two dimensional”.

They are not emitted simultaneously. The collision is messy. The GRB comes from leftover bits of neutron star.

This intuition could be completely wrong

It isn’t.