It might be a primary vs general thing. Palin has to be popular everywhere among Republicans. Less so in New England, maybe. Maybe Palin is viewed unfavorably by fewer Republicans in California than in New England. Even if it is New England, I would think Schiff would want Palin’s support.
The concern I’d think would be that her primary support would harm the Pubbie position in the general. Schiff needs a hail mary to have a chance, and I suppose that would be Palin.