Is mother's milk a disrespectful submission?

As an MMA user when I had thrown my opponent to the ground multiple times and got above my opponent, they sometimes try to defend themselves a lot, specially their arms, and the easiest thing I could think of is mother's milk to enter submission, I had done this technique a lot of times, and I found out some hours ago that it's disrespectful to do that, so I'm I a bully now or something in my MMA class?