i haven't got any specific thoughts about how to most simply open up access without strong trust guarantees but i bet you'll come up with some other ideas

for now, the best i've got is second level - the follows follows - follows mutes... but to actually make all this work there needs to be an active process scanning the network for relay lists and asking for mute and follow lists

it's gonna take a bit of thinking i think, for now i have the basis... i can open up relays to people just by adding their key to my owners list and whoever they follow is automatically allowed, and who they mute is not (obviously mute overrides)

gives me some ideas about multi-level and scores ranking distance from the owners and using that to scale the timestamps so that trusted stuff is deleted after less trusted stuff, this is one idea starting point anyway