Because they thought Django was going to win best picture and she would get to present the award.
I can't tell if you're actually serious (I have trouble with that lately).
I'm almost positive that they knew in advance that that wouldn't happen.
That could be what we should be talking about.
The White House had to know in advance what film would win, so as to avoid embarrassment.
So much for all the supposed secrecy about the results.