Two observations from me, at least one of which maybe seems to have gone unnoticed.
I have seen 3 different interviews on the night, with different people/channels. In all 3, he said the exact same things, some word for word. So no, this was not a he flipped, spur of the moment rant of emotions getting the better of him. It was planned, and he knew what he was saying. And why. And as others have pointed out chose his timing perfectly, he might well have been waiting a few games to say it.
The second one, one of the most telling moments seems to have gone somewhat unnoticed, where he gave away what really drives him. When he said, I dont want to be a team of happy flowers, I want to beat Arsenal. Loved it. For all his, 'I just want to see my team play like they can', 'I don't care about the title I want to see the desire', 'one game at a time' talk, he fucking wants it, he wants it bad. A brief moment, but showed his true drive, and I was delighted to hear it.