I think it’s normal (sexual?) negotiation among budgies. Nobody got hurt. He was interested and tried to turn up the action. She said “knock it off”. He continued and a flock mate was upset by the increased tension and stepped in. I think if someone begins to have injuries, feather loss, be harassed all the time or kept away from food dishes, that’s a problem. That’s not happening yet, right? And I WOULD make sure that the Quaker doesn’t accidentally hurt any of the little guys.
So if either of your budgies, but most likely the girl, starts to get run down or missing feathers or stressed/depressed, I would intervene. Now I would keep an eye on them. It looked a little obnoxious but I am sure I’m sympathizing with the female budgie. Yet, neither is injured.
Do you WANT mating and breeding behavior to be happening? I guess I don’t know if budgies mate outside of breeding condition so am not sure if you should be concerned that they’re possibly getting ready to breed.
Interesting that Laura had written most of what I observed. It makes me more confident in my interpretation of what’s going on.