As suspected, the voices in favor of the removal are those of the ranchers and advocates, as explained in a June 30 letter to the editor of the Rio Blanco Herald Times.
“The Makeover [chaired by the author, a public-lands rancher], along with the Piceance Mustangs volunteer work [the advocates], have shown the high level of community support our local White River office of the BLM have for their long awaited and much needed mustang gather.”
The writer went on camera a few weeks ago complaining about the horses and her grazing frustrations on two allotments near the HMA, identified in this map.
The advocates went on record in favor of the roundup a few days later.
The letter was signed by Deirdre Macnab, Meeker Mustang Makeover, not Deirdre Macnab, 4M Ranch.
The BLM has not posted any information about the incident in the usual location, a nice example of the bureaucrats, ranchers and advocates working together for a horse-free future.
Western Horse Watchers Association 
So sad and so frustrating