The decision to use UEB math or Nemeth is an agency/state decision. The first article you mentioned would only apply if your state/agency is using straight UEB to do math books. The second lets transcribers know how to use Nemeth within a UEB context (using UEB only for the literary text and using Nemeth for the math). If your state/agency is sticking with Nemeth, these guidelines should be used for the whole book. If you are using UEB math, no Nemeth symbols should be used in your book.
Cindi