The Maharz”u has a number of interesting insights into this medrish. He says that the medrish is telling us there was a set time for Noach to enter the Ark, [not before or after,] and there was a set time for Noach to leave the ark, [not before or after,] and even though Noach desired to leave early and even prayed to Hashem to “get off this boat,” nevertheless he did not leave when he desired but rather when he was commanded to disembark.
The Maharz”u goes on to explain the parables the medrish relates about the chief supporter and the sage. Hashem is the chief supporter of the world, giving everything its proper sustenance. But when he brought the flood onto the world he gave the “keys of sustenance” to Noach and Noach was in full charge of feeding all the animals. That is how Noach had enough food to feed everybody; Hashem gave him the “keys” or means to do it. Hashem is also the ultimate sage who is able to figure out and differentiate between everyone and everything’s needs; how much food should be given at any one time. Noach was given the task and lived up to the task of weighing and giving out food for each animal at their proper time, day and night, until Hashem said ‘your time is over and it’s time for you to give Me back the “keys” and leave the ark.’
The Maharz”u had a bit of difficulty understanding what happened next because it sounds from the medrish that Hashem promised never to bring a flood again while Noach was still on the Ark. But the Torah explicitly says that Noach first brought sacrifices to Hashem on dry land?! (Parenthetically the Maharzu points out, Noach sacrificed in Yerushalayim on the alter which Adam used to give offerings after he was banished from Gan Eden. This will also be where Avraham performs Akeidas Yitzchok and where the alter will be in the Beis Hamikdash. There is even a stone formation there to this very day!) Furthermore, didn’t we say earlier that Noach had a burning desire to leave the Ark to the point that he actually prayed to Hashem to leave, so why would he refuse to go when he was commanded to?
Therefore, the Maharz”u concludes that Noach certainly left when he was commanded to, but not with the proper intentions, for Hashem commanded Noach and his family to leave the Ark and procreate and replenish the world but Noach refused to procreate until after he brought sacrifices in Yerushalayim ,intending to arouse mercy from Hashem so that Hashem promised and swore he will never bring a flood to destroy the world ever again.
The answer lies in a very difficult but important tenet in Judaism verses human psychology, the notion of why Hashem seemingly brings so much suffering into the world. In the eyes of man, pain and suffering is a horrid state which no one naturally would wish to live through or even observe. That is why Noach did not want to procreate the world, since the thought of future generations potentially going through the same destruction, pain, and suffering that he lived through would not be worth it,in his mind ,to be responsible for such a situation to potentially come about. What he didn’t realize was that his solution wasn’t any better or was actually worse, for a world without humanity has no purpose and that is the greatest evil. That is why Hashem specifically commanded Noach and his family to procreate, so that there will be purpose in the world.
In a similar vein we find in the Haggada that Lavan was potentially worse than Pharaoh for Lavan wanted to wipe out the entire Jewish people by killing Yaakov and his family whereas Pharaoh just decreed that all the boys should be thrown into the Nile. How can Lavan be worse than Pharaoh, who wrought so much pain and suffering onto the Jewish People? It must be that wiping out a whole race or family, leaving no purpose to there existence, is worse than all the pain and suffering Pharaoh brought upon us.
On a humanistic level it is understandable that one might think that suffering, pain, and destruction is the worst, and in fact it is nothing to sneeze at. But Divine insight understands that there is a purpose, an ultimate plan for such such pain, suffering, and destruction but ceasing to exist, which causes a loss of purpose,is much worse.