As much as America would like to think their laws apply across the globe, they don't actually have jurisdiction over you. There's nothing they can do to prevent you from talking about the campaign.

They do have jurisdiction over the candidate and campaign you endorse, though. If you contacted your candidate and offered them money or services in the hope that they could use your help to get elected, and they accepted your offer they would be guilty. You wouldn't be.

Unfortunately, it seems like a fairly impotent law if all you have to do as a foreign national with an interest in the election is to support a candidate without their endorsement.