If people had bothered to read the article you would see the statement.
“Most people don’t realize that what kills people during a pandemic is not just an influenza virus, but a secondary bacterial infection,” said Ramanan Laxminarayan, director at the Center for Disease Dynamics, Economics and Policy in the United States, and senior author of the study.
The purpose of building up a stockpile of anti-biotics is to allow treatment of secondary infections for those that need it.