I would not expect that detail in the news reports. However, if true it would come out at trial. But even then it might be a defense attorney gambit.
My speculation is based on what sounds like the overreaction of the family, which wouldn’t make sense for a simple assault, but would make a lot of sense for a sexual assault. The final part of the speculation is the tardiness of the D.A. office to file charges.
Time will tell.
The action of the family is consistent with the behavior of people in fights at Walmart, in the subway, in schools, in parks, at “Stop the Violence” concerts ...
I don’t think any “explanation” is needed other than that one of their people was “dissed.”