You started with masks, not social distancing, so sticking to your original argument, I'd say that link you provided just indicates that masks worked well enough to protect the protestors, even without considering the social distancing aspect.
Were you going to address the comments regarding your statement that people aren't wearing masks or are you just going to ignore them and try to find something else to reinforce your narrative about the 'participating demographic'?
People scream at the cops, without masks. The same for chanting. You can either muffle yourself, or lower the mask and project loudly.
With a few hours of intense marching, people naturally want to remove/adjust/lower the mask to talk/shout/run. Even with those wearing their masks, their effectiveness won't be 100%.
Which leads back to the OP's point - if the virus is airborne, why don't we see an uptick in deaths for that demographic?
Because the 'participating demographic' skews young.
“We estimate that susceptibility to infection in individuals under 20 years of age is approximately half that of adults aged over 20 years, and that clinical symptoms manifest in 21% (95% credible interval: 12–31%) of infections in 10- to 19-year-olds”
You're arguing for how effective masks are in stopping this virus. A fact that it'd be nice if more people accepted. And is great info that the protests demonstrated so.
The protestors are in the age demographic that are by far least affected by the virus.
“We estimate that susceptibility to infection in individuals under 20 years of age is approximately half that of adults aged over 20 years, and that clinical symptoms manifest in 21% (95% credible interval: 12–31%) of infections in 10- to 19-year-olds”
That was my experience in June. Crowds were packed but nearly everyone had a mask. It makes me think the masks are more important than social distancing (at least outdoors), but I'm not gonna stop social distancing where feasible. I was very pleasantly surprised that people didn't get sick.
The crowds are tight and packed.