> If I bring a compromised device on your network
Then I'm in real trouble with or without this. A compromised device can sniff the network, masquerade, inject network traffic (inc. DNS), and can attack every other device on that same segment.
> I don't need code execution from an existing internal resource.
If you cannot execute code in an internal context then you cannot exploit this bug, you'd effectively be an external attacker. Your own example had you running code on a locally connected "BYOD" device. Therefore you're already executing code in that context.
> Why wouldn't you patch internal servers for this anyway?
Nobody suggested that. In fact quite to the contrary.
By the way while we're discussing niche edge cases, what's your strategy to protect against Van Eck phreaking? Seems about as concrete as the attack vector you're proposing (local network access with no way to execute code).