Yusuf the Apostate?

Should we understand from quran that the Islamic 'prophet' Yusuf was an apostate?

S 2:133 Or were you witnesses when death attended Ya’qub, when he said to his sons: What will you worship after me? They said: We shall worship your god and the god of your fathers, Ibrahim and Isma’il and Ishaq, one god. And we are Muslims to him.

He was originally a Muslim? But in the following verse we read:

S 12:37 He said: Food you are provided with does not come to you but I have informed you of its interpretation before it comes to you. That is of what my lord has taught me. I have left the cult of a people who do not believe in Allah and they in the hereafter, they are kafirun.

Did he at some point apostatise? If Islam is true, should this Islamic 'prophet' have been killed?