That's true, but any actor doing this will probably have the budget and know how to use something more malleable than a Wi-Fi transceiver - for those new to RF, examples might include software defined radios or (much more expensive) a custom RF product with better bit-depth (One can buy a 10GSPS ADC for a few thousand bucks these days, a three letter agency could easily make a bunch of them).
Using standard gear is less suspicious though. And if you have a hacked machine on the other side of the airgap you may not have to place any gear at all.
