Mika not joining the board battle was the right move. He's where he should be, and Olafsson is checking him tight. Kreider is able to get the puck out of the scrum and swings it out. The puck DOES NOT head straight to Mika; it goes a little bit wide to his right.
Let's say Mika, instead of remaining stationary, reacts and makes the read on Kreider's pass. He activates away from Olafsson, goes to the puck. Then Fox would see that and drift to the net at a different angle and look for a pass from Mika. Mika would take Kreider's pass and sling it to Fox right away, and it would be Fox feeding Lindgren for the goal.
But it is Fox who makes the read. He gets to the puck, which would've been in no man's land in the low circle, because Mika remains where he is, doesn't really move. He dishes it to Mika. Olafsson has to protect against a crossice pass from Fox to Lindgren and commits, goes down. He's out of the play now when the pass goes to Mika instead. Yeah, Mika is NOW in the right spot, in the right time.