Issues with this study.
Bold point 1: These surgical team members are presumably not infected with any transmissible virus, so this experiment is really only testing if there's any difference in surgical site infection among
healthy mask wearers vs.
healthy non-mask wearers. I would venture to guess that a healthy non-masked person won't transmit/shed much of anything, mask or no mask.
Bold point 2: This suggests the study had a fair deal of selective sampling, as was elaborated in the following sentence of the most rigorous test only sampling non-scrubbed mask wearers.
Addition criticism: In a real world social setting, there's too many confounding variable to assess the efficacy of masks due to human behavior variability. Are the subjects wearing them correctly? Are they keeping them on their faces? Do they keep fiddling with it and touching their faces (which could facilitate transmission)?
The simplest experiment you can devise to test if masks work in a vacuum is having subjects cough, talk, and sneeze into a culture while wearing a mask and then wearing no mask and then comparing particle load differences. This study did so and found that viral coronavirus load was significantly reduced.
https://www.nature.com/articles/s41591-020-0843-2#Tab2
The pushback against masks is puzzling to me. It's a cheap, non-oppressive way to reduce transmission. Is wearing a mask while you go grab some bait and tackle at Burt's Fishing Hole really that big of a deal?