Well, after hunting this down, it turns out the dump is not what breaks wifi. The dump is caused by the kernel attempting to load the regulatory.db but it is not loading the required /usr/lib/crda/pubkeys/sforshee.key.pub.pem. The kernel config sets CONFIG_CFG80211_REQUIRE_SIGNED_REGDB=y which requires validating but .pem is not used. I think libnl should validate, I do not know enough on this topic.
Will this prevent nfsroot over wifi? Maybe, untested.
But this is not the cause of the missing wifi devices, and so what is? I am not exactly sure. But the good news is I know a “fix”. It seems adding net to HOOKS causes the need for:
FILES=(/usr/lib/firmware/updates/brcm/brcmfmac43455*)
But now I can nfsboot on wired without breaking wifi.
Edit: Adding another group of files cleans up another boot error but it does not seem to effect anything. I believe user space applies the required configurations.
FILES=(/usr/lib/firmware/updates/brcm/brcmfmac43455* /usr/lib/firmware/brcm/brcmfmac43455*")