I've had a couple of t2 MBP's refuse to run OS and security updates on wired connections. We aren't blocking anything and it seems to run on wireless just fine.
Is this how the t2 firmware functions? My educated guess is that the firmware for ethernet over usbc is not accessible in the preboot environment, but I'm having a hard time (imagine that) finding any Apple documentation to back this up. Or any documentation for that matter.

