I'm agreeing with you, they could have chosen to not do the exchange face to face but they went with a different option and instead met at a safe space.
What I'm saying is most of the conjecture about the "why's" is constructed to place blame on the person who didn't murder anyone, people are even going as far as suggesting she should have known that her new boyfriend would kill her ex outside of a police station which ignores the reason someone would meet outside of a police station.
why the boyfriend brought a gun to an exchange?
This is looking premeditated