It's not DCA's job to tell the corps what they can and cannot play, nor is it really possible to pass a rule stating "corps can't play any music DCA cannot secure the synch rights for". It's not the corps responsibility to even inquire about synch rights (unless they plan to release thier own media....but even then the pricing may be vastly different). Corps are responsible for arranging and performance rights. Period, stop.
And let's be honest...DCA (and DCI) abused copyright for so many years, it's a wonder the rightsholders will even have a conversation with the two circuits all, let alone sell them synch rights at an affordable rate.