If you're unwilling to trust Tailscale and their processes, you can't run Tailscale right now. That's obvious. It's part of the premise. The idea that ACLs "mean nothing" is risibly reductive; the ACLs protect our team members from each other and mistakes they might make with their environments.
(We don't use Tailscale SSH, and are unlikely ever to; we have a separate source of authentication truth for SSH, and a separate certificate-based access control system.)
They built a footgun into a toaster, and victim blame when people complain that they thought it was just supposed to make toast. Users should not be put into a situation where they need to configure ACLs in anticipation of undocumented features.
My hope was that with a little public prodding they would do better in the future. It is a product I want to like, maybe not for what you or I do, but lots of folks out there are slinging cat pictures where it will be a net benefit.
"Victim blame". They announced an opt-in feature.
Until you decide to ship a completely on-prem Tailscale server, ACLs mean nothing. They can be modified by the same rogue employee that added an SSH server that bypasses local firewalls to our environment without telling anyone.