If Spider engineers didn't even bothered to change any of the BSD userspace utilities what is the chance that they built the entire TCP/IP stack perfectly compatible with the outside world inside the kernel from scratch?
This remind me a particular incident happened to Brendan Gregg of the eBPF initiatives, when a company performed a demo of their alleged game changing kernel tracing tools to him and as it turned out the tools were actually Brendan very own developed tools.