If the horse respects you and will stand for thefarrier FOR You, then you tell the farrier “No, I'll hold him.“ Who owns the horse? You or the farrier? The farrier is there to trim hooves. You are there to control your horse. If I let the farrier or the Vet's assistant handle my mule Maggot, it's a dang Rodeo. She doesn't respect them and I'm not having them screw up my mule. Now, that said, if you can't control the horse to stand well for others either, you need to start working on that.