It’s based on the long-held (but censored) fact that Covid has always been “aerosolized” and not spread though “large droplets. The only way for masks to be effective would be with “large sweat-sized droplets.
If interested:
https://www.cnbc.com/2021/04/23/mit-researchers-say-youre-no-safer-from-covid-indoors-at-6-feet-or-60-feet-in-new-study.html