[dipper]

My first advice would be to not let your dog run loose on any property that you do not have control over.
I NEVER go to dog parks or community areas were dogs run loose or anybody can show up with any dog and let them run--it's a recipe for disaster.
Like my Vet says " I hate dog parks but they're good for my practice---honestly I should set up a booth there on the weekends!!". He says this in a sarcastic manner as he really does hate them.
What if that dog decided to take an ear off your pup?? And, you had a 2 year old in your arms??

Dogs don't think like we do and size has little to do with the reaction of a dog.
Some petite women weighing little more than a Rottie can be and are excellent trainers---it's not about size and muscle.
My neighbor has a little terrier that weighs about 7 lbs. that took on a female whitetail deer with a fawn---that deer tore her up but she kept at it until she was knocked out and that little terrier of hers will challenge ANY dog that walks on her property.

Even though your dog is only a year old, it seems like it will be more of a submissive example than a dominate one---but he has a ways to go in his development.
I would not put him in a situation like that again if at all possible.

Rich