Patriotism doesn't just hinge on being a separate isolationist. People from Yorkshire, or Fife, or Cornwall, keep their pride in their own area despite being a part of the United Kingdom (still united and may it stay that way)
Buying local food, supporting local manufacturing whenever possible, cheering your own football team, is not suddenly forbidden.
We can be a part of a larger whole without losing identity, and exert a positive force within it and through it. If we leave, the EU and the millions of people in greater Europe would be poorer for the loss of our influence and experience, and so wouild we without our many links.
He is right, not all of it is about trade - though that is a big factor.