Years ago I went to see the brilliant Peter Osgood at a football talk-in. He was one of the pioneers of "soccer" in the USA after a stellar career in England. Back then, a lot of the American soccer teams played their games on plastic surfaces. He was chatting to one of the American players and asked "do you prefer grass or astroturf?".
The American lad's response was exactly per your quote 
.
Stadium tours have stopped for now and will resume around the start of next season. Tours wouldn't feasible (or safe, for that matter) with so much work going on in the stadium/with the pitch. For the graduation ceremonies the tunnel area/dugouts gets covered by scaffolding and a stage, so that entire area is out of bounds.