Tailscale hired the guy who wrote Headscale, for him to work on software, so they're sponsoring the programmer who's working it, but it's not "Tailscale" software, and they have no warranty, express or implied, because it's not theirs. It's its own project.
I am pretty sure they would have eventually published a control server.
We just happened to be quicker (and come up with a great name, IMHO).