big IF the attacker wouldn't harm a young girl. If the guy attacked a big snake without just cause I would assume they would attack a girl they think is possessed.
That's actually the point of the exchange. We have seen — both in the manga and for ourselves — that understanding does not mean there will be no conflict. But the spirits don't have that experience, because they're spirits. When spirits understand each other, there is no conflict, but that is not true for humans.
MC understand this, and that's why he's dipping. If this human is willing to attack spirits that are ostensibly more powerful than him in pursuit of whatever he's after, then it stands to reason that he'll do the same to
anything that he thinks is an obstacle, including some meddling kids (with or without a puppy).