Brilacidin was tested against COVID-19 in the late stages of the disease and failed, just like the other drugs tested from Big Pharma. IMO, this left NIAID undeterred because they could see that the evidence from the COVID-19 clinical trial suggested that B could be effective as a prophylactic.
IMO, again, NIAID was undeterred by B's failure in the late-disease-stage of COVID because they gained new data that suggest, at least in terms of COVID, that one of B-AV's roles in the therapeutic treatment process could be prophylaxis.