Given the consequence of a false negative for both of those diseases (fatal if not treated), it makes perfect sense to optimize for a higher negative predictive

Given the consequence of a false negative for both of those diseases (fatal if not treated), it makes perfect sense to optimize for a higher negative predictive value (if the test says you don't have it, you don't have it) versus a higher positive predictive value. While it would be ideal to have a high rate for both, that's the one I'd choose. And that false alarm rate is actually a dynamic function of the prevalence of the disease in the population being tested, which would make me hesitate to call it "useless", especially this early in its development. Those values, for the record, aren't that much worse than rapid diagnostic tests for influenza, which have a False Positive rate of about 6% and a false negative rate of about 18%, assuming 30% prevalence.