This actually seems like a remarkably elegant solution to the above problem. I'm hesitant to make it domain linkable though. A cool kind of solution to ambiguity would be a graph network, say "join team X with members X,Y" to identify the team uniquely. And that is referenced to the people you're linked to on keybase, and the groups they're in. If a group by the same name exists with the same named people, it shouldn't be picked over the correct group, and if it were, you would be rejected from joining the team.