First I believe it should be the plane of blue line. It shouldn't matter if the skate is down or not. Second, he was so far ahead of the Blues defense that inch offside did not affect the play in any way.
I could certainly be down with the plane argument, but that's not the rule as it is written now.
As for the other, you never know what happens if he has to sit there and wait at the line instead of getting in ahead of the puck. He could trip over the line from his flat footed start, fumble away a bouncing puck landing at his feet, etc. I've seen dumber things than those happen in games.
If it didn't matter to him on some level, he wouldn't have tried to time it so closely.