I think we are all proving the author's point here.
For my decisions, the assumed intent of the rule was slightly different than yours: no potentially fast-moving objects that might cause severe accidents.
So: no cars, no bikes, no skateboards. RC toy cars with low mass are okay. Rowing boats are not okay because they might harm swimming people. The surfboard on the beach is okay because it is not moving fast within the park. Etc.
And we're showing why the author is correct: because a lot of people jump to conclusions, hold fast to their assumptions, and assume everyone else thinks like them; even after having had it all clearly explained with a tailor-made interactive game, and even in the face of abundant direct evidence to the contrary.
For my decisions, the assumed intent of the rule was slightly different than yours: no potentially fast-moving objects that might cause severe accidents.
So: no cars, no bikes, no skateboards. RC toy cars with low mass are okay. Rowing boats are not okay because they might harm swimming people. The surfboard on the beach is okay because it is not moving fast within the park. Etc.