By the way excavators already have the ability to move with material in their buckets. I'd think that pause logic works the same way as reassignment logic, but if changing one would mean changing the other, there'd absolutely need to be a difference between the two, as changing an excavator from a coal mine to an iron mine for example would cause the next truckload of material to potentially contain both ores, in turn needing explicit ore sorting settings temporarily.
If this wasn't the case, you could still do this exploit anyway by just reassigning excavators between worksites. And you're back at square one. I definitely don't think this to be anywhere near the priority of a lot of other items in their backlog