He chose Mandarin so he could help with WWE's growth into the area.
Honestly...
While it is impressive that Cena spoke Mandarin...
It was below average.
I am a fluent Mandarin speaker...
Since that is my parents' first language...
But I only understood about 40 to 50% of what he said.
The accent is way too thick...
That I could not decipher some of what he said...
And the grammar is off in a fair bit of instances.
That said...
That was enough...
For me to guess the gest of his message...
But I really do not understand why a lot of commenters said it was good.
Nowadays...
Caucasians who speaks Mandarin is no longer a novelty.
In fact...
A lot of them can speak the language fluently.
Edit:
Ok...
I gave the speech a second try...
And I think I understood the whole thing now.
I may have been too harsh on Cena upon first impression.
Sure...
It is still not great...
And it needs multiple viewings...
But his grasp on the language is somewhat passable for a foreigner.