not true, i dont use bench wheel to polish kirbys at all any more and they get to a mirror shine. just takes a lot of sandpaper working up to finer grits, transmission fluid, and your arm falling off. but it CAN be done.
yes i learned it from a volunteer bus restoration im working on polishin aluminum. does the job of mothers and mineral spirits together and less toxic.... yes less toxic. ATF even generic cheap stuff works great with the wetsand method.
Whats the steps you do? I normaly sand my kirbies starting at 200 grit and moving up to 2000 grit. Then I use my bench polisher with the coarse then fine polishing compound.