OP I was in that woman's situation at work a few weeks ago and would have appreciated someone, anyone, speaking up for me.
What's worse it that I work in a place where the customers involved were people I have known for many years.
One of them, who had had too much to drink, just snapped, and I was the one who bore the brunt of his aggression.
He snapped at me and just started shouting, swearing, banging things about and just screaming and ranting at me.
We were outside, in a small enclosed patio area, and I tried to get back inside to get away from him but one of his friends blocked the doorway and started shouting as well. He repeatedly blocked my way with his arm and pushed me back towards the other man.
So I walked the other way, towards a gate at the other end of the patio, to try and escape, but the man who was shouting abuse at me came at me with his fist raised to my face and I thought he was going to punch me. He was shouting a threat at me as he came at me.
I stopped dead and he picked up a chair and threw it at me.
At this point his friend disappeared so I was able to get back inside and ask for help.
What made it worse was, there were about ten other people sitting and watching all of this, including his girlfriend, and not one of them tried to stop him, not for his sake or for mine. As his friends, I think they could have intervened without risk to themselves, but they thought it was funny.
His girlfriend and another woman, who has known my family for twenty-five years, sat and laughed all the way through it and they thought it was hilarious when he threw the chair.
While I was trapped between the two men, both of them shouting, I was actually pleading with those women that I just wanted everyone to leave. They wouldn't go.
When they thought we were calling the police, the girlfriend started shouting abuse at me and my colleague and the other woman lied to cover up for the man who threw the chair at me.
Now the woman who was laughing is offended because a couple of days later, while I was with my husband, I pointed her out as one of the people who had watched the men shouting and who laughed when the first man threw the chair. Apparently she didn't like being looked at, yet she seems to think I shouldn't be upset at having a chair thrown at me by a customer because she's still trying to maintain he threw it 'near me' but not at me.
The only reason that chair didn't hit me is because I stopped moving and ducked.
I wouldn't expect someone to involve themselves if they were at risk of being harmed, or in your case if they had a child with them. But I've been out with DS before when he was in his pushchair and called the police from a safe distance when I saw a man screaming at and grabbing a woman who I think was his girlfriend, and then also attacking a man who stopped to help her. I stayed on the phone to the police giving them a description of everything that was happening until officers arrived to help.
I think that's possibly the best thing I could have done in the circumstances and I'd do it again without hesitating.