zzzzz You are quite welcome to attend a playgroup where 7mth od babies get hit with wooden & plastic blocks while mum looks on having nothing to do with the situation.
I on the other hand, will not accept my children hitting another child, nor will I allow them to be hit. I don't care what the circumstances are.
And perhaps a lynch mob would work. I am genuinely shocked that you think this is in any way acceptable.
So if they said, "XX lost her father and is behaving quite aggressively", or "XX is recently adopted and displays some difficult behaviour", or "XX is epileptic and her Meds make her aggressive", or "XX is developmentally delayed and is over a year behind her chronological age" would you honestly run for the hills because you only want to hang out with the naice kids?
It has NOTHING what so ever to do with only wanting to socialise with NICE kids. My children have been hurt by kids, the difference between that & here is 1] the parent IMMEDIATELY apologised & 2] it was prevented from happening again!
As I said, if the staff & the mother was passive & weren't dealing with it, then yes, I would fucking leave! Yes, the kid may be upset, but letting them batter other children is NOT the way to help them...since when has children hitting each other been a reasonable therapy tool for grieving toddlers?
The SIMPLE point that you are MISSING is that there NO explanation being given for the behaviour. Mum hasn't even apologised, ffs! Just sat & watched. If the child is grieving/on meds & hitting out, there are ways to prevent it & you should ALWAYS apologise. Not let it go time after time.