I have a feeling the bristly reaction, even though the photo was manipulated, comes from the understanding that not everyone who sees the photo will realize it's a composite. The ones with dinosaurs chasing the wedding party, etc., are probably a little less controversial because there's very little danger that an idiot will put someone in danger by posing them with a real dinosaur, but with train tracks, I'm afraid that might be an actual possibility. The point is that while you were smart enough to take the proper precautions, someone imitating this photo might not be. It's unfortunate, but it's probably something that needs to be taken into consideration.