As "jego" is the emphatic form, I wouldn't use it here, at least without more context. It just sounds strange. "Oni go nie znają" is perfectly fine.
Thanks for the reply.
I've heard that "jego" generally goes at the beginning and end of sentences, whereas "go" in the middle of sentences. Is this a good way to think about it?
Well... for sure at the beginning (but that's rare anyway, that sounds very much like correcting someone: "Jego kocham! Nie ciebie!"), and for the end... well, it should generally be avoided, so if you use it, it also gives the same emphasis. Let's just say that its natural usage is rather limited.
Why "znają" is correct but "znaję" for I know is not correct I know=znam. "Piję"= I drink I thought all verbs should end in "ę" if i refer to myself