This list largely consists of those who signed the Not in My Name petition. Some who are not on the list perhaps have been somewhat chastened at the outcry that arose from their shooting off their mouths in the last couple years and did not sign the petition. I would put Jennifer Anniston and Brad Pitt in that category.
This list is the most recent incarnation of Hollyweird stalinists. Some of the lefties have probably decided it is best not to shoot off their mouths and sign anti-American petitions.