As you said there's global and local concepts of trust. Just like a relationship there's global standards of what breaks trust (maybe kissing someone else) but then local that "override" it (maybe some couples are ok with that). [Oh know... A thread]???

I think at a protocol level just like browsers there should be some obvious defaults that are also public. Browsers default isn't won't record audio without permission for example. On your protocol I'd say a default would probably be like "no hate speech".