OK, forget about it.
The badge criteria are solely used to issue/award the badge and are not re-evaluated at a later moment.
In other words, and in my example: if a user doesn't belong to the audience anymore, the badge is not automatically revoked.
I follow Paul's remarks: this makes it impossible for us to continue with badges (and in our case certifications). Our certified partners really want to show their badges on social media and we have to make sure the badge expires when the related certification expires.