To helicopter, or not to?

For background, my son will be 2 in January. He's at an age where he's getting pretty competent around play equipment, but he's also usually the youngest one there (or thereabouts).The other day I was at the park with him and there was a child who I'd guess was about a year older than mine (so still quite young) who, for whatever reason, took a disliking to my kid and decided to single him out. It was nothing too bad, whenever he spotted him he'd run up to him and push him onto his butt in a non-playful manner, he wouldn't let my kid go down the slide, and pushed him out of the way a lot. The worst it got was when he tried to sit on my son at one point.My kid wasn't hurt, but it was upsetting him and he was getting mad and a bit confused as to why it was happening.Obviously, my first instinct was to jump in and help my child, which I did. But I've been thinking that maybe it would've been better to back off and monitor the situation from afar. Maybe this is an opportunity for him to experience something while I'm present and able to help if needed? The idea of not helping him when he's being bullied hurts my heart to think about, but what would other parents do here?Is it better to teach him that I'll always jump and help him out when I'm around, or should I allow him to navigate it and see if he can work something out?Edit: obviously the ideal outcome would be that the other parent puts a stop to it. I'm not mad at her, she did stop it once and was apologetic, but the poor woman was also wrangling three older children who looked like a massive handful, so she didn't spot it till I'd already jumped in. via /r/Parenting https://ift.tt/2E4BHxh