What he's saying is that this is a retrospective that's looking to blame outside reasons for the outcome of a vote, when ultimately the reason a vote went one w

What he's saying is that this is a retrospective that's looking to blame outside reasons for the outcome of a vote, when ultimately the reason a vote went one way may simply be genuinely because most voters felt that way. In hindsight you can blame a million externalities for any 'undesirable' result in any election, because there are a practically infinite number of factors, foreign and domestic, involved in the elections of any major nation. For instance imagine leave lost and chose to play the same game. In mid April 2016 Obama blew to the UK to try to do a mixture of evangelizing against Brexit and implicitly threatening the leave position as well by suggesting that Britan would be 'at the back of the queue' in any future US trade deals if Brexit passed. And one can only imagine the thousands, if not millions, of pro-remain posts and topics shared on social media by people outside of Britain. Of course these ended up being completely pointless and Obama's visit actually ended up strengthening the leave position, but cast in a different light these sort of externalities could be used to try to argue for undue and undemocratic influences that led to the result of the election. But it's revisionism.