Apart from the fact that the article itself says that it has a lower mortality rate than the original one and that those data refer to mices (which makes all the possible difference), as it's obviously not possible nor sensi Al to experiment on humans. Bio and pharm fields require experiments like this one all the time, which can be counterintuitive for people from outside. I'm not really following this exact case, as I don't have time to properly read the paper, but it's likely been done because this will help knowing better some cellular mechanisms, or could be used to develop better vaccines / antivirals... You can be safe knowing that it's a common practice and people who work on that knows how to handle samples. The founds are low enough to not waste them on something unless it's undeniably useful