Viral load reduction by X % is not exactly same thing than killing X %. BUT, in case of Brilacidin it is, in my opinion, acceptable simplification in order to get the point across. Especially because Brilacidin probably kills viruses by 'popping' their protective membranes, some other antivirals act like viral prophylactics.
"I would rather have questions that can't be answered than answers that can't be questioned." Richard P. Feynman