I know this probably goes against RAI, but I can not find anywhere in the Core book where it says that a specialist wizard can not take the universalist school as one of their opposition schools.
On page 79 of the Core book it just states that a specialist wizard must choose two other schools as his opposition schools. On the same page, it references the "universalist school" several times. Then on page 82, the Univeralist School is listed under Arcane Schools.
So, being that the universalist school exists, and that all schools (except his own) are available to a specialist for choosing as an oppostion school, is this allowed by RAW?