Not enough evidence for what? Quote:

"The evidence is admittedly incomplete for all the steps in COVID-19 microdroplet transmission, but it is similarly incomplete for the large droplet and fomite modes of transmission. The airborne transmission mechanism operates in parallel with the large droplet and fomite routes [16] that are now the basis of guidance."

By using arbitrarily high standards for evidence, I might as well claim there's no evidence that COVID is transmitted by large droplets or by smear infection. Where's the randomized trial that proves beyond any doubt that coughing in each other's faces will spread COVID?