It sounds like electors could change their vote, at risk of fines, but then Soros would be sending them a fat envelope for their trouble.
I don't think so. This last bit seems to rule that out.
Today, it is rare for Electors to disregard the popular vote by casting their electoral vote for someone other than their party's candidate. Electors generally hold a leadership position in their party or were chosen to recognize years of loyal service to the party. Throughout our history as a nation, more than 99 percent of Electors have voted as pledged.