Headscratchers / Thunderhead

After Roscoe Swire told the other expedition members that two of his horses had been gutted and killed the night before, why wasn't there a more urgent reaction from the other expedition members? At the very least, they should've informed the Sante Fe Archaeological Institute of this development during their daily radio exchange. The Institute could've called for reinforcements (e.g. a SWAT team, a National Guard unit) to be sent to their location by helicopter to protect them from the horse killers. If this was not possible, then it would've made sense for all the expedition members to leave Quivira as soon as possible, rather than having Nora and Smithback go on a side trip while the others stayed in Quivira until they returned.