Then the point we are making is that your “helping” your friend’s son is going to potentially hurt his chances as that most selective private colleges. It does look from the posts by @ucbalumnus that he can waive out of the language requirements for UC admissions, so if he simply wants to apply in state he should be o.k.
But private, “top” colleges: for every kid like your friend’s son, they will have a dozen applicants who are going above and beyond high school requirements. It may be that it’s unrealistic for the kid to aspire to Ivy or elite level colleges anyway – from what you have described he sounds very narrowly focused in his interests, and at the same time there is no indication that he has done anything beyond or outside the high school curriculum in those areas.
So bottom line, whatever chances he may have at elite admissions, those chances will be reduced if takes options that, as noted above, raise questions in the minds of ad coms. Easy enough for the ad com to take a pass on the kids who apply with an obvious gap in their high school curriculum.