Well, they don't have to kill them to challenge them or chase them off. Our cats at home will (and have all) taken on coons in our backyard before. They sound like screaming children when they fight, it always wakes us up. So far, there hasn't been a coon that's won the fight- but there's not been deaths on either side, so I assume the coons take off because it's not worth it to fight the cats. Three of ours don't even have claws and they still have at it... but our cats are pretty big, I think our smallest is 12lbs.
Cats and coons here tolerate each other but the coon would most certainly win a fight unless it is a bob cat and then the coon would high tail it outta there and not come back for a while i have seen this on my trail cams.
So what are you doing with your surviving peafowl? Did you turn them loose or are you keeping them in the same pen in hopes it won't happen again? Hoping for the best possible outcome in this situation, I think about it alot now with my peafowl, but mine sleep on top of their 12 foot pen. I bet yours might do the same, and if a coon came near they would fly off into the trees, even in the darkness they could have a means of escape at least.