Always is your responsibility even with tailscale. Now it is his responsibility without tailscale.

Attack surface almost entirely goes away if you just require a good port knock first! I do that with my protection SSH servers and it works just fine. Also prevents anyone from knowing there even is an SSH server there. Or any server if it doesn't respond to pings either, and only uses reverse tunnels to accept public connections

With AI, the complexity doesn't really matter anymore. Codex or Claude can easily configure complex site-to-site setups and peer configurations on mobile devices. I did this by hand before and it was hard and difficult to get right. Now I just tell AI and it does so perfectly, checks and verifies things. AI made life so easy.