why did Rock accepted Cena's offer?

This Monday night RAW the Rock said that he accepted Cena's offer but still people can't understand why he did that? 

He told in his speech that he accepted his offer because of some reasons

1.He and Cena hate the Miz and R-Truth

2. WWE Universe wants to see the Miz and R-Truth getting their worst defeat ever.

3.He want Cena to know what he is capable of. 

 but if we look at each and every point, no reason make sense. Does he hate Miz and R-Truth more than he hates Cena? Why would he listen to WWE Universe after all? And why will he be Cena's partner to show Cena what he is capable of? He can also go in the ring and give a beating to Cena to show waht he is capable of doing after all.

After all of this it can be said that maybe Rock wants to be friend with Cena but don't want to agree this in front of people or he want a little support of fans but he would be keeping something in mind which is nearly impossible to know until he tells.

at Survivor Series John Cena and Rock vs Awesome Truth (Rock and Cena team up never before never again)