No proof at all, it's just a convenient talking point to evade the reality that this kid was acting as a responsible and civically  engaged person.  The deflection to the mom is just that, an evasion of the actual facts.
I was a scout and started getting involved in politics when I was twelve.  There was no pushback, as scouts are taught to be civically engaged.  It was a presidential election, but I'll take the fifth on the year of that election.