I understand that you’re protecting your kid, and there’s nothing wrong with that. Pull her aside.
But assuming every “muscle dog” is bred to kill is ridiculous. The dog likely saw you playing and just wanted to join. He was trying to be nice and show that there wouldn’t be a problem, which you absolutely don’t have to accept, but that doesn’t make the dog aggressive. Just let it be. Especially if he’s just walking by. He’ll be gone in a second, just let him go.
Smaller dogs are statistically more likely to bite a kid than any other breed