Noah shook his head when he saw how distraught she looked over those people she believed weren't worth it, he just couldn't grasp her attachment. His assurance that they were "doing fine" wasn't a lie; from his perspective, they were. Despite the fact that their fate could be sealed if they were swarmed by sprinters, Arachne's swift elimination of many before they reached the group, coupled with Ailetta's overly determined use of her zombie, left them with manageable numbers to contend with.
Realistically, Noah's argument held validity, but it was rooted solely in logic, lacking any semblance of human empathy. Despite the mitigating factors, people continued to perish. The sprinters' suicidal tactics, charging straight into the group without regard for their own safety, forced the group into a defensive struggle where not everyone could be shielded.