I find it very curious how a movement that purports the benefits of education frequently looks to children as leading figures. I'm not a fan of hers and I voted HP, but I also have sympathy as I see that she's being used by adults.
I am more sympathetic to this tactic in this case than I am in many others because a focus on the future is a core part of the political argument being made - ultimately, it is a play for empathy by putting a face to the consequences which the recipients may not themselves live to see.