Well there does exist a monkey fist style called 猴拳 or hou quan. But I am not sure if there really exist a technique called baby monkey that uses a close guard position like BJJ. In the majority of Kungfu styles there really is no ground work like BJJ because the era and thoughts behind it were not practical.
Is it possible that a monkey stylist used this technique maybe but I like to think it was not in the intent that BJJ use it and more of a result of trying to find another method of defense or attack.
Joe Rogan's comments is biased I think because most people would consider the Lei Tai 擂台 were matches were sometimes fought to the death, San shou 散打 were the idea really is to throw the person hard enough to knock him out. Cung Le is famous for San shou and who has competed in UFC making Kungfu having been in UFC
Not so much. He's a Hung Ga guy that runs a CMA supply store.
He has a video out "touting" Hung Ga & how other styles don't measure up. He had one of his students (I guess) throw a Sow Choy "from CLF" to demonstrate a point. Let's just say his knowledge of CLF is right about there with monkey boxing.
Just take him with a grain of salt, chuckle & move along.