For the same reason people in Japan occasionally invited me as a guest speaker to their English speaking clubs-- because they wanted to learn the language better.
Learn it better. Not learn it from scratch. Some fluency was expected by the clubs.
Then there's this part - If you wish to affirm an ethnic, racial or religious identity through school, you will have to go elsewhere. We will end all ethnicity-, race- and non-American nationality-based celebrations.
So then if a religious identity is verboten then I assume no Christmas? Just 'Happy Holidays'?