Why did God disapprove of the exemption granted by the Holy Prophet to the hypocrites from going to fight (with the army of the Roman Empire)?

Verses 43-49 of Chapter 9:

May Allah forgive you. Why did you grant them leave, until those who told the truth were manifest to you, and you had known the liars. Those who believe in Allah and the Last Day, would not ask your leave to be exempted from fighting with their properties and their lives; and Allah is the All-Knower of those who have Taqwa. It is only those who believe not in Allah and the Last Day and whose hearts are in doubt that ask your leave. So in their doubts they waver. And if they had intended to march out, certainly, they would have made some preparation for it; but Allah was averse to their being sent forth, so He made them lag behind, and it was said (to them): "Sit among those who sit (at home).'' Had they marched out with you, they would have added to you nothing except disorder, and they would have hurried about in your midst (spreading corruption) and sowing sedition among you -- and there are some among you who would have listened to them. And Allah is the All-Knower of the wrongdoers. Verily, they had plotted sedition before, and had upset matters for you, until the truth (victory) came and the decree of Allah became manifest though they hated it. And among them is he who says: "Grant me leave and put me not into trial.'' Surely, they have fallen into trial. And verily, Hell is surrounding the disbelievers.