If you think about it, a lot of birds "dance", make noise, and usually puff up and look big while courting. While there is definitely a difference in mating behavior and aggressive behavior it has it has a good deal of overlap. A lot of birds will fan out their feathers to look big in defense as well, they often get loud and may flap around. It's easy for people to look at dance in humans as unique. But really we have a similar thing going on to birds. We have sexy dance like salsa. But we also have intimidating dance like what the Haka like New Zealand rugby team does. Or how foot soldiers would bash sheilds in unison going into battle. We loved battle drums. It makes sense that music and dance could be connected to intimidation because healthy humans are likely the best more coordinated dancers while less able (sick,old, disabled, very young) are less coordinated people and less able to have large ranges of controled movment. Dance says "I'm healthy and socially confident enough to move around like this infront of others"