According to the Insigna Guide 2002-2004 Clause 4. Prohibition of Alteration or Imitation.
(a)"No alteration of, or additions to the official uniforms, as described in the official publications, or the rules and regulations covering the wearing of the uniform and the proper combinations thereof on official occasions, may be authorized by any Scouting official or local council or any local executive board or committee, except the Executive Board of the Boy Scouts of America after consideration by the Program Group Committee"
So to answer your question. No they would not be considered a part of the "official" uniform. However I, personally, like the idea of the zip off pants. Maybe someone should submit the idea to the BSA Program Group Committee.
