Despite my preference for the SteamDB method, I fully support using the centered Wilson score (proposed here for answers) - (positive+2)/(positive+negative+4). The only thing that really matters for this specific proposal is that the observed average quality of contributions be adjusted according to the number of contributions.
Further, if desired, we can go even simpler: define trust thresholds as a pair - (average quality, number of contributions) - and require that both be exceeded before a particular privilege is granted. That way we can pretty much abstract away whether we’re using a centered Wilson score or SteamDB’s ranking algorithm.