Brionon-why muzzled?As Boo says,most dogs will chase a cat.Even my dog,the friendliest dog in the world will chase cats and squirrels if she sees them,even our own cats occasionally just for fun,and if their not in the mood they wack her nose!
Just because this dog is a big rotweiler (incidentally known for not getting on with cats) there's no reason to suggest it will attack a child. If he hasn't got him on a lead he must think he's not a problem.
It might be an idea just to talk to him one day,jellybean,if you say he lives in your road then there must be an occasion when you can 'bump into him' and maybe say hello to the dog.Maybe then you can see if the dog (and the guy) is friendly,
To have it muzzled is a bit of an over-reaction just because it chased your cat.If it happens again maybe you could suggest he has the dog on a lead near your house.