Amazing. Reading more carefully, as FabHK pointed out above, they aren't even applying the obvious correction. They're just reporting the positive rate of the imperfect test. I've implemented Diggle's method [0]. When I have time, I'll see if they've provided enough data to do a proper analysis, and maybe write a blog post about it or something.
[0] https://github.com/indralab/opaque/blob/761572ed1b0d601271f0...