It's not anything to do with her being problematic - WB will not license this as it literally boils down to not selling the same products in different locations to the same market. That works both ways, for WB having their own Studios Tour and extremely high rent retail locations (selling the same Merch as Universal), and for Universal needing Brits to continue to go Florida for longer trips as well as this park for shorter trips. Replicating anything is going to cannibalize Orlando.
And yes theres a small chance Minion Mayhem will be in both parks, but nobody is flying to florida for that ride.