Final Game(s) Report - Girls 8th

[SamIAm]

End of season tournament (8th Grade girls A-Team) -
Nothing of note Friday or Saturday's early game. That brings me to the championship game.
The Play-
20 pt lead 3 minutes left in the 4th qtr. B23 forearm push from behind to A1 while shooting a "clear path" layup. All other defenders trying to catch-up with the play. Weaker of two officials on the play.

U calls the foul and reports, no cross. Coach allowed to attend to A1. R stays with A1 until coach arrives. R and U meet and discuss. No additional signals given. 4-5 minutes of delay later as A1 is being tended to, R gets A1's sub to shoot free throws with lane cleared.

B23 did not return to the game.

Of course the crowd is rumbling as same two teams played last week in season finale and B23 committed same type of foul on same A1 (I didn't witness that event as I was at sons BB practice). One less-intelligent and uninvited parent went to the scene of the crime. Then her spouse joined, not sure why, maybe to extract the buttinsky. Nothing but murmering and vocal complaining came of the event. The play itelf was cheap as opposed to B23 not knowing how to foul properly, IMO. At dinner later with a teammate's family I explained that the situation was handled as it should have been from a game point of view.

The question that I don't know the answer to is:
Some kids surprise you by doing stupid things. If a kids stupid actions doesn't surprise the coach, is the coach at fault for inflicting that player upon other players?
Is it a coaches responsibility to not play a known knucklehead?
(Not by any BB rule I am aware of).

I will attempt to get ask the R what the ruling was.