I commend OP for helping non-English speaking passenger. It is unfortunate and sadden me to see an agent interacting with non-English speaking passenger like that. This agent was pretty much implying that non-English speakers cannot fly commercial flights in the U.S.

It will surprise me to learn that AA has English speaking requirements from passengers. I highly doubt TSA has any language requirements. TSA is federal government agency of the U.S., and the U.S. has tried to pass official language but never has. The U.S. does not have an official language recognized by the government.