I think the $9 billion was what California spends on illegal immigration. "Completely sealing the border" means an Israel-style wall or Duncan Hunter's double fence at 15' (someone said that was already $3 Billion to build from the Gulf of Mexico to the Pacific Ocean) which then frees up border patrol personnel to concentrate on interior enforcement - so yes I assume that means "roundups and mass deportations" - anything else you need to know to answer the hypothetical?