Perhaps it's because once you pass the commercial written, you're done.
But the author of the interpretation should read the first part of the rule:
" ...on the aeronautical knowledge areas of paragraph (b) of this section THAT APPLY TO THE AIRCRAFT CATEGORY AND CLASS RATING SOUGHT..

On Wednesday, June 12, 2013 10:34:24 AM UTC-7, Thomas Van de Velde wrote:
The question on whether VOR/ADF is a required subject for FAA glider ratings has come up on this mailing list but without a conclusive answer. I've recapped another recent discussion along with input from the FAA on my blog:



http://flightbit.com/2013/06/11/to-vor-or-not-to-vor/



I hope this clarifies the confusion on the subject.



Thomas