Dear Br. Shabbir,
I think Mr. Mansour is saying that Allah did not detail the prayer (timings, units, what to utter, etc.) because as He knows the present and the future, he knew that Muslims would have no problem observing the prayer in the future so he did not detail it.
Mr. Mansour seems to be asking why explain/detail something which is clear and Muslims observe this ritual since childhood (without any problems) based on what their parents teach them and have no need for any guidance!! He is saying that Allah only provides guidance for those areas that were more important!!