Might be nice to expand on "will not work". Wouldn't 5 GHz Wi-Fi failing to connect show that it's even better at blocking, and would easily block 2.45 GHz too? And I'd think that they should block 5 GHz too, since those meshes look quite fine, and they probably try to be extra-safe.
However I do agree that it's probably still gonna work because the faraday cages on microwaves are always overkill (even the cheap ones).
There really isn't any substitute for a proper EMC chamber.
In this case it could be the opposite: faraday cages only work for blocking wavelengths that are longer than the wavelength that it's designed for (presumably 2.4ghz). Therefore it could be blocking 2.4ghz but letting 5ghz waves through because it's too small to contain.