Why?
Because since Christ gave the great commission, men have traveled to foreign lands to share the truth. Many could not speak the language of countries they went to well, nor write as well, but God used them to bring others to Christ.
If you think there are Americans who could not learn from him due to his lack of knowing proper American English sentence and grammar structure, then you do NOT know God. Besides, looks to me like many here thought he did a pretty good job.
Let me know when you write someone in Nigerian to bring someone you know there the truth, or any other country foreign to you.
Then we can talk about who is not worthy of listening to.
News for you, I will be sharing other commentaries he writes, because I think the more he has a chance to do so, the better he will get.