> TCP syslog...which is durable and attestable to in courts.

TCP alone won't get you there. It's certainly not durable in and of itself. All TCP can do is ensure that streamed data is received in the correct order, and confirm that a segment's data was successfully placed into the right buffer on the receiver side. You also need immutable storage, stronger integrity checks than what TCP itself provides, and many other requirements I haven't researched in a while.