I noticed you mentioned the danger of the road to them last time.Yeah, I kind of liked that white lie idea too. If it comes to more serious intrusions, it's an option to consider. However, I don't want to be that neighbor that is known for putting out poison that could kill their pets, so even a white lie about poison might not be in my best interest.
That is a genuine danger to the dog, but not one that would be your fault. So warning them about it makes you look like a good person instead of a bad person, while still pointing out that the dog itself is in danger.