>>I'm sure a 777 can make a 90 deg turn, even if tight-ish.<<
OK Betty - you work it out... how far ahead of the main wheels is the nose wheel and therefore how deep into the corner would the aircraft have to go to ensure the left mains stay off the grass.
I've had a look at it on google and it doesn't look doable. Turns greater than 90 degrees are particularly difficult. It's easy to say it doesn't look doable after the fact. When you can't see much from the flight deck it's easy to get into a tight spot in a wide (long) body. Even the cameras don't help that much.