The doors of the Palace Arcade could be opened from the front facing the street and used as an entrance/exit for the Tribute Store and continue using the far doorway as another entryway (the one that is by the bathrooms near the pizza place). Everyone’s focused on the door connecting to the Munmy exit being open but they could simply leave it closed as it is now and separate the two that way.
If Universal does plan on using that door to get people in and out I was thinking they could use stanchions to direct people leaving the ride directly to the Mummy gift shop exit door, or at least prevent them from immediately going left after the first on-ride photo checkout kiosk and allow guests the option to go that way further into the room. It would require rearranging the gift shop a little first.
I would’ve suggested maybe splitting that doorway in half so people exiting would use the left side towards the lockers and people coming in from the street could use the right side of the door but it’s a tight space.