So far he's tried it once in competition (Nebelhorn FS) but popped it and was clean for the rest of the program.
Outside of competition, he's even tried it in the SP if you remember. At least twice this year in the SP that we know of, if not more. Tartu camp gala and Knowledge Celebrations gala. Both times was UR and maybe two-footed (at least the first one was, not sure about the second one) but he didn't fall.
Edit2:
And quite frankly, he might not even get to go to Euros if he doesn't have a quad in his layout, regardless of where he ends up at Nationals.
My question is, if he was allowed/told to try it once in competition, why not anymore? And yes he did try it twice in gala performances, and no he didn't fall. Doing something at a gala is, based on my experience, pretty comparable mentally to doing it competition.
He also most probably will need the quad at nationals to even place high enough to go to euros. And as an added goal, so to say, worlds. We know it and Sasha knows it, so nothing new here.