If one (a male) gets excessively sexually aroused. And sometimes while talking to non mahram women, his private part gets….

Even though he isn’t aroused, but his private part reacts nonetheless. And it happens with other people too. Can one ignore this in this situation, and continue on talking with the people, because the person isn’t aroused, but his body reacts this way.
What should be done?

As long as he does not feel lustful intentions while talking to the opposite gender, it would be ok. Otherwise he would have to end the conversation.