California public universities do not appear to specify any restriction on accepting transfer credit for college courses taken while in high school, including in dual enrollment situations or where the college courses also fulfill high school graduation requirements.
If the student has exhausted the high school’s offerings before 12th grade (e.g. has taken the highest level of math, AP or otherwise, in 11th grade) and wants to continue to more advanced courses in that subject, then should s/he refuse to take an available more advanced course at a nearby college? I.e. look at the question more in terms of the student’s academic interests and development in subject(s) that s/he is interested in.