It would be justified in Texas due to a child being present. Also what he did in the laws of this state was to commit a sexual assault by exposure. (Legal wording of the charge could be a little different.)
Besides you do not know what the man would do later. The woman was in a park with her 6 year old child, and man not only exposed himself he stated that the woman should watch. Who knows what he would have done or tried next.
No matter how many times you do it and nothing happens it only takes something going wrong one time to kill you.