Definitely not a cultural thing. And it would have been equally gross if it were the son, only then it would perhaps also have been more dangerous. It's not just that he's old that makes it gross, it's the abuse of power. Maybe not physical strength as power in this instance, but the "power" he gained from Fuji girl's politeness. Yukk! And here you'd been respectful to him all this time. The total breach of trust and respect makes it even more revolting, because it makes it so much harder to be civilized to the next neighbour who moves in. Good luck getting over this. Hope it doesn't ruin neighborliness for you.