As far as I know, Lootmaster can only be enabled for DF content. As timeworn maps are not part of DF content, it cannot be 'Lootmastered.'
This would be a great feature to have though. I've seen many map items go to the wrong guy, and it's always resoved with a quick trade, it does kinda hold everyone up while they figure it out and /slap the guy a couple times.