It’s definitely not on and given he can’t take a no I think it’s best she stops going there.
When I was really young, under 20, I was approached by an older man in the street who asked me out.
I was mortified. I said no and carried on walking, he followed me and started having a go at me to and to give him a chance. Total lunatic.
My point it, he might be a deluded older man or he could actually be one of those men who can’t take a no and get ugly.
If she’s uncomfortable and he’s not stopped it’s best to avoid the situation all together.
It’s wrong that a young woman can’t even volunteer without unwanted hassle, but sadly it seem women still have to alter their behaviour because of men.
He’s not doing anything illegal by asking her out but morally he is in my book.