Except that this will only really matter on Friday and Saturday nights (at least during the school year), and how many adults do you know who like to wander the mall (especially the Pheasant Run in Nashua) on a Friday or Saturday night? There are better things for adults to do at those times. This will kill the Pheasant Run. I've been there, and nearly half the stores there are aimed at teens. If they can't hang there, they'll go down to the Burlington (which is bigger and better anyway, even if it is a bit further).
Assembly Sq. Mall in Somerville MA had had it with the Asian and Hispanic gangs terrorizing the customers, so they had security toss them. A Massachusetts judge (bwa ha)said this was a violation of their right to Freedom of Assembly. Now, there is no Assembly Sq. Mall.