That is a bug I missed in my original script. Sorry! I should ask, though, do you just want that for the artist, or do you want the album/track title as well? If you mean the former, that's already handled by the MusicBrainz sort fields (or if it isn't, the name in the database needs to be updated) and unless you don't also want "Lastname, Firstname" for traditional, human names, that can be solved by simply not using the sort names as the staging point:
$noop(Swap the fields for the iPod)
$noop(Copy the temporary fields back into the primary ones)
$noop(Clean up after ourselves)
If you only want the group names to be sorted without "A" or "The" (and have people sorted under their first name), that's a bit more difficult because of the multi-value tags, but could probably still be done. I'd rather not put in the time figuring out how to do that if it's not going to be necessary, though, so if that is what you want, let me know and I'll get digging.
For the titles, I'm actually using the next script in my own library. It will still run into issues with multiple values, but given that, most of the time, those fields should only have a single value (and most players wouldn't know what to do if there were multiple), that shouldn't be anywhere near the problem it is with the artists.