True, the patient could receive treatment. The risk, given a pre-existing condition, to become infected with the virus is still an additional burden, but perhaps not death. Conversely, some number of people with pre-existing conditions, who chose to avoid hospitals and who did not die as an outcome, could have also died had they visited.

I imagine that the people who chose to stay home are in a set where it wasn't obvious that staying home meant death. Thus, I think it was a good bet given what we know about coronavirus complications, spreadability, and virulence.