I actually think it's one of his more well thought out tweets in recent memory. So much so that I highly doubt he wrote it. Trump doesn't congratulate people who beat him; he claims that he won anyway. Compare and contrast to another tweet from last night:
The reason I originally endorsed Luther Strange (and his numbers went up mightily), is that I said Roy Moore will not be able to win the General Election. I was right! Roy worked hard but the deck was stacked against him!
That's classic Trump: incoherence; lies; and the ability to claim he was right when he was so wrong.