So how are you getting the Twitch Id (account Id)? You are still required to know the exact username to lookup the Twitch Id.
Your response implies you set and forget your whitelist, because if you are demonstrating your extension to a lot of different people, the current system of adding/removing Twitch Ids isn’t very convenient.
An improvement would be to use the Twitch username as I mentioned. This can be accomplished by clearing the whitelist for every new version and providing a way to lookup valid usernames, similar to registration forms. That way if the user has changed their username, you will be inputting the current one, which is active vigilance of your whitelist and not just setting and forgetting it. Additionally, if someone’s current workflow is a set it and forget it type, then the previously used whitelisted usernames could be used to quickly repopulate the current version’s whitelist. This can be accomplished a number of different ways and implies you know the people you’re whitelisting and if they’ve changed their names. Lastly, it’s easier to identify the username than an Id, which is a reason why DNS exists.