Nah, doesn't matter if he's a loader, sorter, etc. It may vary by area, but I got my extra dollar after only loading feeders for 4 months.
You can qualify for the dollar by either getting trained (and learning) how to pickoff or sort in a sort aisle and then showing proficiency
or
You can get the dollar by learning how to load all loads on your belt if loading feeders, because it stands to reason if you know every load then you can send any package to the correct slide.
This is past practice anyway, and how I got my dollar. I didn't start picking off or sorting in the sort aisle until quite a bit later. I've also heard of people getting the dollar by simply passing the sort test on the computer, even if they're not working as a sorter on a regular basis.
Now, the above being said, it is possible that since they put the thing in the scanners that the feeder loaders use that beeps and stops them if they scan a misload that they no longer give that for just knowing all the loads on the belt. *shrug*