Because the last time it came up (at least that I specifically know about), they were quick to allow a DPE to do it.
A DPE cannot give a 44709 exam. Let me qualify that, A DPE is not suppose to be designated to give a 44709 exam.
My reference: http://fsims.faa.gov/PICResults.aspx?mode=SubjectCategories&area=05&subject=02®ulation=all
FAA Order 8900
Conduct a Reexamination Test of an Airman under Title 49 of the United States Code (49 U.S.C.)
5-1422 INSPECTOR QUALIFICATIONS. Inspectors must be qualified in the aircraft. An inspector conducting a reexamination test shall hold the same aircraft category and class ratings that the airman is being tested on. (A designated pilot examiner shall not conduct a reexamination test.)
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But many things happen that are not in the book.....