Another significant factor might have been the draft Desert Renewable Energy Conservation Plan (DRECP). Under the BLM's preferred alternative, the Juniper Flats area would be designated as an area of critical environmental concern (ACEC), and a smaller portion of the area would be brought into the National Landscape Conservation System. This put the wind project on a collision course with the DRECP because energy projects that do not have a published draft environmental review within 60 days of the draft DRECP's release would be subject to the DRECP's land designations (DRECP Volume II, page II.3-312). North Peak Wind almost certainly could not complete a draft environmental review before the end of 2014, and would have been doomed by the DRECP's decision to designate Juniper Flats as an ACEC.
Fans of the Juniper Flats area are now asking to expand the NLCS designation to cover more of the area. You can sign a petition in support of the NLCS designation at the Alliance for Desert Preservation website. Although the ACEC status alone would prevent new energy applications among the hills, the addition of NLCS status would probably make the conservation status more enduring.