Well, if it was not the end of the game and the other coach did nothing I would quietly and respectfully pull him aside and have a chat. If said coach condoned trucking a player at a friendly I would just pull my team.
Coaching in a game about 7 years ago, squib hit towards 1st. Spins away, 1B goes to knees to grab ball, pivots to tag. Girl running to first veers in and lowers shoulder. Is on the ground bleeding and concussed, havering over her and reading the riot act to the ump because there was zero action taken and, while there over my payer the other coach had the audacity to walk and start saying "come on, you know that was incidental contact". Never been thrown out of a game but that was the closest I ever came. At 6'5" I was more than willing to have incidental contact with that coach every time he came to 3rd base box. I refrained because I know it would have been absolutely the wrong thing to show the players but it would have felt great.
Long story short, trucking a player by another player is bad, a coach condoning it reprehensible.