Slowing down isn’t a universal answer. Define slow. I rode at an average of 15 mph, and got passed constantly. Was I slow or fast?
I started off saying the cyclists shouldn’t have reacted the way they did. But that doesn’t change the math. If the parents had recognized the inherent danger of multi-use trails (because they are inherently dangerous, lots of random going on out there) and done a better job of controlling their the entire incident doesn’t happen.
“Slowing down isn’t a universal answer. Define slow.”
If you don’t have an innate sense of what’s a slow enough or safe enough speed around pedestrians, especially 3-year old toddlers occupying the same pathway as your bicycle...I can’t help you.