They asked her to tell him.
Natasha knows she is the most likely choice, and truthfully, she wouldn't have let anyone else break the news. It was going to be hard enough hearing it from her. Out of all of them, though they all loved him, Clint will take it the hardest. They might have lost a friend, but Clint lost so much more.
Steve is defeated, head hanging low. Bruce is silent, because he didn't know the man behind the title, but he still has respect for him. Tony is his usual blustery self, but he is fooling no one. Thor feels guilty, because Loki was responsible.
And Clint…Clint still doesn't know.