Most people assume the threat is the FBI or the Chinese or something; it's not that MUDs are some high-value intelligence asset, but consider what anyone could glean by deploying a packet sniffer on your LAN and reading your traffic to/from it. That it's MUD traffic is immaterial.

Same goes for local LLMs. Most UIs don't offer HTTPS enabled by default, so you're broadcasting your most intimate thoughts on the same network segment your malevolent stepchild uses. Apps make amateur spycraft for BPD-types easy.