Sorry for the late reply, DD!
Oh man, this has my blood BOILING. If you’re overprotective for that then I am as well (I told off a kid for pushing A’s hand out of the way when she was playing with a toy at Toys R Us.)
That man was RUDE and clearly isn’t teaching his child good manners. I told my husband about it and he said that the father is an idiot (アホ).
When my daughter was younger, actually probably around Shimi’s age, so many parents would tell their child to be careful or wait if Anzu was around because she’s younger than them (赤ちゃんがいるよ！気をつけて！”).
Now that A is three, my husband and I absolutely tell her to be careful around younger kids. If there’s a small toddler going up the stairs of a slide, I usually direct my daughter to play with something else until the slide is free. Now she does it on her own!
Unfortunately, I think there are idiot parents out there who don’t think kids are old or smart enough at a certain age to be careful around others. It’s sad, really.