The part here relevant to Heads (coreboot, replacement of proprietary firmware or reflashing a custom firmware) is that otherwise proprietary have a tendency to lock their users into using a subset of hardware components, here on Lenovo, this is whitelisting supported wifi cards.
On proprietary Lenovo firmware, you could not replace the wifi card. When using coreboot, you can.
Why Atheros? Because they are recommended and supported FOSS devices. Thinkpenguin and others are reusing same chipsets which are RYF certified, which is the path of choosing lesser evils.
Outside of that, this is not related to Heads/coreboot.
On hardware/design flaws of Intel wifi cards:
iwlwifi had design problems disclosed Low Level PC/Server Attack & Defense Timeline — By @XenoKovah of @DarkMentorLLC
Qubes (Xen) had XSA-404 which questioned security of sys-net with hardware components related design flaws
For Bluetooth and other device removal/replacement, this should also probably be discussions happening in other threads.