Branson / Virgin exposed Corbyn for being a liar, so this does look a little like sour grapes.
Virgin is a big UK employer and Branson treats his staff somewhat better (e.g. unlimited holidays) than, say, Philip Green treats his. I do think Green should lose his knighthood as his morals and ethics are below "chivalrous" standards.
Personally, I think people can choose to live where they want and that people who live in the UK, and businesses who operate in the UK, have a duty to avoid legally as much tax as they are morally comfortable with avoiding, especially if said taxes were going to fund the kind of loony policies that Corbyn and McDonnell would put in place.