The FCC just released the actual order from yesterday's 5G wireless broadband "Spectrum Frontiers" rulemaking. The Commission declined to consider the 47 GHz amateur band. I am reading the order to see if they said anything about why they aren't.

 FCC TAKES STEPS TO FACILITATE MOBILE BROADBAND AND NEXT GENERATION WIRELESS TECHNOLOGIES IN SPECTRUM ABOVE 24 GHZ.   New rules will enable rapid development and deployment of next generation 5G technologies and services.  News Release. (Dkt No RM-11664 97-95 14-177 15-256 10-112 ). Adopted:  07/14/2016. News Media Contact: Charles Meisch at (202) 418-2943, email: Charles.Meisch@fcc.gov  OET IB WTB  https://apps.fcc.gov/edocs_public/attachmatch/DOC-340301A1.docx
https://apps.fcc.gov/edocs_public/attachmatch/DOC-340301A2.docx
https://apps.fcc.gov/edocs_public/attachmatch/DOC-340301A3.docx
https://apps.fcc.gov/edocs_public/attachmatch/DOC-340301A4.docx
https://apps.fcc.gov/edocs_public/attachmatch/DOC-340301A5.docx
https://apps.fcc.gov/edocs_public/attachmatch/DOC-340301A6.docx
https://apps.fcc.gov/edocs_public/attachmatch/DOC-340301A1.pdf
https://apps.fcc.gov/edocs_public/attachmatch/DOC-340301A2.pdf
https://apps.fcc.gov/edocs_public/attachmatch/DOC-340301A3.pdf
https://apps.fcc.gov/edocs_public/attachmatch/DOC-340301A4.pdf
https://apps.fcc.gov/edocs_public/attachmatch/DOC-340301A5.pdf
https://apps.fcc.gov/edocs_public/attachmatch/DOC-340301A6.pdf