I did a copy edit of the article, and among other thing, I put the section back in.  After reading the Ethnic Group page, I felt that the term could apply, although this decision is based upon my limited knowledge of the terms "Flemish" and "Walloon" (I am, after all, not Belgian).  In any case, if the phrase "Ethnic Group" is inappropriate, simply replace the term with a better one, as the data is pertinent to the article. -