The founders would roll over in their graves to hear that someone thinks their constitution allows foreign dynasties to fund American candidates.
They'd probably underline the provisions about only land owners being allowed to vote, and the senate electing the president.
In Russia handing leaflets on the street is considered a political activity. If you narrow it to financing political parties, you are right. But political parties are not NGOs. If they receive money from abroad by way of NGOs it is still a problem of political party funding, not NGOs.