TB54 this extension is designed with email as the unique identifier for all accounts, so it's impossible to not read the email without re-implementing everything in a different way.
Even with a different token as unique identifier (Twitter login is actually not email-bound, because Twitter accounts can have no email), Flarum still needs to ask for an email as it's used for all account recovery operations as well as email notifications.
It's technically possible to remove emails from Flarum entirely, but it's a lot of work as users are fundamentally email-based by default.
