The authors say this:
> The most important limitation is that the findings are inconclusive, with CIs compatible with a 46% decrease to a 23% increase in infection.
This is not saying that that study is inconclusive. It's saying that the protective effect is inconclusive -- masks could be anything from slightly protective, to slightly harmful. The fact that the writer characterizes the entire paper as "inconclusive" is incriminating: it's an editorial bias, a complete misunderstanding of statistics, or a combination of both.
> Which sounds like their saying they can say with 95% confidence that there is between a 46% reduction and a 21% increases, which sounds pretty damn inconclusive to me.
No. They're stating the confidence interval on the point estimate. All point estimates have confidence intervals, and the existence of a confidence interval does not mean that the result is uncertain. To restate basic statistics: the top-line conclusion of the study is that the 95% confidence intervals of the two groups overlap to such a degree that you can't reject the conclusion that they're the same.