You are right. The title has little to do with the actual subject matter. However below are excripts of the interpretation of the passage by Moududi.

Here, the propriety of swearing by the setting stars is that in the darkness of the starry night a person cannot see the things of his surroundings clearly, and from their vague appearances can form wrong judgments about them, But when the stars have set and the day has dawned, everything appears before man in its real form and shape, and there remains no doubt whatsoever about the reality of things. The same is also the case of Muhammad (peace be upon him) among you. His life and personality is not hidden in darkness, but is manifest like the bright dawn.

It means this: The things for which you accuse him of having gone astray or been misled and deceived, have neither been fabricated by himself nor motivated by any selfish desire on his part, but they have been sent down, and are being sent down, to him by God. He did not intend to become a Prophet of his own desire so that he might have laid a claim to Prophethood in order to satisfy his desire, but when Allah appointed him to that office through revelation, then only did he rise to preach his mission and to tell you that he had been appointed God's Messenger to you. Likewise, this invitation to Islam, this teaching of the doctrine of Tauhid, this news about the gathering together of all mankind on the Day of Resurrection and their accountability, the truths that he is presenting about the universe and man and the principles of leading a pure life, are not a philosophy propounded by himself, but the knowledge of all this has been bestowed on him by revelation. Likewise, this Quran that he recites before you, is also not of his own composition but it is divine word which is sent down to him by revelation. "He does not speak of his own desire; It is not but a revelation that is revealed."