Going to be great for the pro-Brexit side. No electorate likes it when a condescending imperial Washington tells them how to vote.
Obama is still popular in the UK; certainly more than Boris is. Had it been someone with the popularity of Bush in his last year in office saying that then I'd agree with you, but not Obama who people still respect.
I suspect that by virtue of not living in the US and having less chances to interact with US leaders, foreign perceptions of domestic leaders swing much more rapidly on the times when they do interact. Our opinion of domestic leaders are cooked far stronger in than our opinion of foreign leaders.
I wouldn't be surprised of Obama's favorables in the UK took a very nasty tumble after this.
