I’d suggest asking about their “No French, No Problem” Curriculum.
My 12yodd is in 7th grade this year. She used their Mission ABC in elementary school. I used it in an auditory:verbal way without emphasis on reading and writing, just listening and speaking. She is doing quite well with level 1, easily translating because of her past listening and speaking experience, but I think it’s written well enough for others to begin without prior knowledge.
She will complete a level per semester until she’s completed each level. After discussing equivalent US credit with the author, I feel confident in giving 2+ credits of highschool French. The author said studying levels 1-10 of MM is easily worth 2 highschool credits in comparison to traditional US language resources, but this will actually be a more advanced working knowledge of the language in both written and conversation skills.
I also like the emphasis on missions and learning the history and culture of the various French speaking countries that are studied in each level.
I’m guessing completing NFNP would be worth one credit you’d need to contact them for their suggestion in your son’s situation.