Qutb's explaination of sura 4 (Part 1)

Qutb's commentary on Sura 4 is extremely long (which may make sense considering the length of the sura itself). So far, I have run across some similarities to the way that he discusses women in Social Justice in Islam. In his explanation of inheritance, he uses the same argument to explain why the difference between men and women is not derogatory, but logical.

However, I do have a hard time following Qutb's argument about polygamy. He seems to me to be hypocritical in his explanation about why a man can take multiple wives. At one point, Qutb writes that a man may need to take a second wife to satisfy his sexual needs when the first wife is old or unwilling. Yet, a page later Qutb says that carnal desires is never an acceptable reason for taking a second wife. I was unable to tease out what the distinction between the two situations Qutb was attempting to make.