“You have an issue you feel uncomfortable about, and feel your safety is threatened? let’s talk with a democratic representative, so they better understand you.” Is not “activism”. It is normal political process in a democracy and it should be endorsed, especially for children. They have rights too and they have opinions too and since they cannot voice their opinion in elections it is all the more important that they can be heard by politicians. And there the bar is also different. A child cannot be expected to form a conscise political argument, leave alone lobby for it, what would be activism. But children have legitimate concerns that need to be heard nonetheless.
By this definition raising any issue with any politician is “activism”. Also who the fuck would deny a child to change its mind as it grows up?