[Deaf Smith]

“he allegedly walked up to the drive through window”

That places the actor beyond the pickup window and the victim at the window.

The actor would have been between the victim's vehicle and the pickup window and possibly between the victim and employee.

The victim would be right in the middle of the argument, trying to receive his order.

Blame the story writer for the use of “intervened” as written.

[HartleyMBaldwin]

The actor would have been between the victim's vehicle and the pickup window and possibly between the victim and employee.

Then the victim would have been in his own vehicle, not between the loony and the McDonald's employee, and thus not "right in the middle of the argument". Until he intervened.