Did you even read it? They're arguing that keeping a strict lockdown for long has too serious negative effects, not that it isn't effective in combating an airborne virus, which it is.
Furthermore, it's from October 2020, more than a year ago. We have vaccines now and they're helping, but not stopping the virus fully. Hospitals are still filling up in some places, and for that various stages of restrictions up to lockdown are the main ways stop it.
