It looked to me like the everton defender didn't jump because he couldn't. You can very clearly see coates's hand on the everton guys shouldersafter he has headed the ball. Irrelevant though if the goals was disallowed for offside.
Has it been confirmed that it was ruled out for offside?
Just had another look at the vid again now.
As he jumped up Coates never touched the defender. It was him leaning forwards/over the defender and losing his own balance that made him put his hands on the Everton player´s shoulder.
And the defender never even tried to jump up and head the ball, just because he would never have reached it anyway - Coates was faaaar above him there!