Can I whitelist specific users so their comments are never hidden?

No, we don't offer the ability to whitelist specific users.

However, we do provide an option to exclude comments containing specific keywords from being hidden when you've activated the "Hide all comments" moderation setting.

With the "Hide all comments" setting enabled, all comments will be hidden by default. You can then add words you'd like to exclude from this filter, which allows those particular comments to remain visible regardless of who posted them.