as with any meta-anlysis, one must make sure the underlying data is relevant to what is being meta-analyzed.

I'm not sure his collection of studies (about half of them) looking at household transmission can be extrapolated to community transmissions. Admittedly, that's because masks can only do so much, but the fact they don't work in preventing transmission between people around each other 16+ hours per day, doesn't really tell us that they won't work preventing transmission between people around each other for say 30 minutes.

Similarly in a couple of others, I'm not sure the ineffectiveness of wearing a mask in a clinic, but otherwise living normally not preventing the transmission of the common cold is particularly meaningful.

The strongest argument against masks by stating "he secondary attack rate of ILI was twice as high in the mask-plus-hand-hygiene group (18 percent) as in the control group (9 percent)" But rather than "masks bad", when the hand-hygiene group is comparably 17 percent, doesn't that suggest something other than masks are at play or at the most naive that hand washing was the key negative factor? The authors point out a similar flaw, the 90% of the households slept in the same room without a mask. If you are spending 8+ hours in the same room as someone is there any reason to expect anything to work? Same flaw.

From all of this, I wouldn't say it's a reasonable conclusion to say "based on this analysis of actual scientific studies of the use of masks, they are at best irrelevant and at worst a detriment."

So, if all of the RCTs lead to an "equivocal" position, what do you do?