You took the correct action. First and foremost, your pup is 15 weeks old. A situation like this can go bad quickly if the other handler isn't on top of her dog. If it went bad, you could end up with an injured puppy and looking at doing some work to avoid having a reactive pup.
Second, a puppy is a bad candidate for cc to begin with simply because it is a pup; wiggly, all over the place, unpredictable. Your neighbor needs someone with a calm, obedient dog to begin this process.
The neighbor's dog sounds like Woolf, in the past. I know I wanted others to cross the street or I would for 2 reasons - main one being I did not want Woolf to get teeth on another dog and that owner end up dealing with a reactive dog also, the other being is the reaction itself is reinforcing - Woolf reacts, the dog leaves, Woolf wins - next reaction can be quicker, stronger.