All of it, every last sentence including the preambles from both regulations and especially the comments to the FAA from interested parties concerning the cost benefit analysis that is a required part of the rulemaking.
You can go to
http://frwebgate.access.gpo.gov/cgi-bin/get-cfr.cgi?TITLE=14&PART=108&SECTION=9&YEAR=2001&TYPE=TEXT for CFR Title 14 Part 108 Section 9, "Screening of passengers and property," to see that everyone must be screened.
Also see my post #114 for Part 107 Section 20:
No person may enter a sterile area without submitting to the screening of his or her person and property in accordance with the procedures being applied to control access to that area under Sec. 108.9 or Sec. 129.25 of this chapter.
I think it's common sense that everyone must submit to security to enter the secure area of an airport.