Unfortunately this is not a Traefik issue but a Silverbullet issue. Essentially, the web server doesn't support a subpath and instead assumes that it is at the root - see https://github.com/silverbulletmd/silverbullet/issues/794 for details.
You can try hosting it from a different subdomain or port instead.
I think the generalization isn't really about white men per se, but about the demographic in power. Give a group unchecked power long enough and they forget how that came to be. I agree that it's not a rule, and maybe should be expressed as more of a heuristic: if you are speaking to someone that is in power, and you don't look like them, they might think you are not empowered.
Don't let the lack of nuance in that statement take away from all the very valid points being made. The plight is real, and hopefully the white men who are enlightened enough to not confuse circumstance with natural order will read and know to not take it personally.
You need a domain name that will resolve to the IP address of the machine running the server. It doesn't need to be your own DNS server. If you already have a domain name, you can just add an A record that points to the IP in your local network.