I think it would depend on the situation as well as the person's appearance. A large framed woman, for example, would probably be less likely to receive violence in return if she was behaving aggressively towards a rowdy group of men leaving, but more likely to receive violence if she was behaving aggressively to say... a group of rowdy women leaving a bar. If a man who was large in build was behaving aggressively towards that same group of women, they might just go back inside and let the bouncer deal or call the police, where as those before mentioned men might return the violence. If the mentally ill person was smaller, I doubt either group would do much of anything because I think most adult people do not want to attack someone who is very much smaller than they are besides they might see them as less threatening than a bigger person. If the person (male or female of any size) was just walking down the road or in a park during day time, I think people of either gender would be more likely to avoid them, ignore them, or call the police. Most people do have an aversion to getting involved in situations that have the potential to escalate physically.
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"...don't ask me why it's just the nature of my groove..."