A client needs to completely disable bluetooth. The most basic level (aside from physically disconnecting the antennas or removing the airport card) seems to be disabling the kernel extensions. 

I looked in `/Volumes/<your system's drive name>/Library/Extensions/` while in recover mode, courtesy of [this question](https://apple.stackexchange.com/questions/341441/cant-boot-macbook-pro-2018-possibly-little-snitch-mojave-related/347807#347807), but there were no bluetooth extensions there. 

Supposedly deleting `/System/Library/Extensions/IO80211family.kext` will disable wifi, but I also ran into issues trying to delete this without being in recovery mode. (Recovery mode shows this file in `/Volumes/<your system's drive name>/System/Library/Extension`, and wifi was successfully disabled after deleting that file from within recover mode, showing `No Hardware Installed` after rebooting.)

**What file should I delete to achieve the same result for bluetooth?**