Thats such a retarded thing to say. Everyone who uses this argument has no idea how the manga industry works. Jump is read by both teenagers and adults. HxH has been running since 98. So the core demographic is all over 25. Just like One Piece, they did a poll and the core demographic of the readers were all above 30.
So, it doesnt really matter if its in Jump, when its targeted towards adults, what matters are the themes, the level of realistic violence and the maturity of the story.