Could be warranted. If they found her using thermal imaging on day 4 then she must have still been warm so maybe only died on day 3. Which would tie in with her being seen moving around after falling.
Waiting for 3 days to die is pretty awful.
They said it was cloudy or foggy earlier and I think thermal imaging does not work well though clouds due to the water droplets scattering the infra-red light. But I wonder if they even tried. Maybe the mist was not that thick.
Sounds like they may not have put as much determination into the earlier efforts to rescue her as they might have.