It may be that buckfastbreeders can go to Chimay with their virgin queens, but I do not really see a problem. If you do not breed melliferas, you have to provide your mating nucs with a drone excluder so that non-black drones can not come out. Besides, normally you fill your mating nucs with young worker bees which are filtered by a queen excluder so that your mating nucs are dronefree.
Gruß,
Dylan