In a video clip from the presidential debate, Trump said, “I don’t wear masks like him. Every time you see him, he wears a mask. He could be speaking 200 feet away from them, and he shows up with the biggest mask I’ve ever seen.â€
Trump was mocking Biden's virtue-signalling grandstanding, not the wearing of masks.
That lie called out, does smart-ass know-it-all Tapper know that in January, February, and March of 2020
the Surgeon General of the US, the CDC, leaders from the NIH, HHS, and the World Health Organization all advised that healthy people NOT wear masks to prevent being infected. In other words, President Trump was following these organizations', "the scientists", advice. Until April these organizations advised that only people who were sick and health care workers wear masks.
January 30, 2020 - CDC recommended against people wearing face masks;
https://www.marketwatch.com/story/the-cdc-says-americans-dont-have-to-wear-facemasks-because-of-coronavirus-2020-01-30January 30, 2020 - Dr. Nancy Messonnier, director of the Center for the National Center for Immunization and Respiratory Diseases, said, "We don’t routinely recommend the use of face masks by the public to prevent respiratory illness. And we certainly are not recommending that at this time for this new virus.";
https://www.marketwatch.com/story/the-cdc-says-americans-dont-have-to-wear-facemasks-because-of-coronavirus-2020-01-30 ;
https://abcnews.go.com/Health/delta-suspends-us-flights-china-amid-coronavirus/story?id=68666037February 13, 2020 - CDC has released new information regarding the use of PPE, including masks; the general public is advised to not use facemasks;
https://www.krqe.com/health/coronavirus/nmdoh-cdc-advise-general-public-against-using-facemasks-to-prevent-coronavirus/February 29, 2020 - Surgeon General Jerome Adams, "(Masks) are NOT effective in preventing general public from catching #Coronavirus";
https://twitter.com/Surgeon_General/status/1233725785283932160March 2, 2020 - Surgeon General Jerome Adams, "(Masks have) not been proven to be effective in preventing the spread of coronavirus amongst the general public";
https://www.snopes.com/fact-check/surgeon-general-against-masks/March 8, 2020 - Dr. Anthony Fauci, "There's no reason to be walking around with a mask";
https://www.cbsnews.com/news/preventing-coronavirus-facemask-60-minutes-2020-03-08/March 30, 2020 - Arleen Purcell, CDC spokeswoman, reiterated existing CDC guidelines that people who are well should not wear the masks to prevent contracting the virus;
https://www.politico.com/news/2020/03/30/coronavirus-masks-trump-administration-156327March 30, 2020 - Dr. Mike Ryan, executive director of the WHO health emergencies program, said, "There is no specific evidence to suggest that the wearing of masks by the mass population has any potential benefit.";
https://www.cnn.com/2020/03/30/world/coronavirus-who-masks-recommendation-trnd/index.htmlMarch 30, 2020 - Dr. Dr. Maria Van Kerkhove, an infectious disease epidemiologist with the WHO said, "In the community, we do not recommend the use of wearing masks unless you yourself are sick ...";
https://www.cnn.com/2020/03/30/world/coronavirus-who-masks-recommendation-trnd/index.htmlMarch 31, 2020 - Surgeon General Jerome Adams, "What the World Health Organization [WHO] and the CDC [The Centers for Disease Control and Prevention] have reaffirmed in the last few days is that they do not recommend the general public wear masks.";
https://www.foxnews.com/media/surgeon-general-explains-masks-public-coronavirusMarch 31, 2020 - CDC reconsidering advice against public wearing of masks to prevent Covid-19 spread;
https://www.washingtontimes.com/news/2020/mar/31/cdc-mask-recommendarions-coronavirus-being-reconsi/It was only in April of 2020 that US public health agencies reversed their advice.