Linguists and multilingual novels

In the book Filipino English and Taglish:  Language Switching from Multiple Perspectives (2001), Roger M. Thompson mentions one reason linguists shy away from studying multilingual texts:  “I could describe the linguistics of written Taglish as it appears in tabloid newspapers, novels, and other written forms, but these are subject to editing and may not reflect everything that is happening in the spoken language.”  Apparently not having realized that Jacques Derrida’s “writing precedes and follows speech” is right, linguists are usually not willing to help multilingual literary critics.  That is too bad, because we critics need the kind of scientific knowledge only linguists can give us.