@snood,
I personally think it's great that international monitors will be there on Election Day. If someone is cheating during this election, I don't much care if an American citizen or a non-citizen catches it. We send monitors to other countries' elections, what's good for the goose is good for the gander.
As far as primaries goes, political parties are private organizations who can have primaries, caucuses, party leader conventions, or any method they choose to select their candidate. Also, the party can change the rules at any time. Monitors don't make sense. I believe what the Bernie-or-Busters are trying to do is confuse the public between cheating and closed primaries, acting like rejection of non-party members from the primary is somehow cheating. It is not, but they are going to pretend it is.