And there are no Sivaite script that talks about Ram or Vishnu. Whereas, various Vaishnavite script say that Siva gave away stupid boons to Asuras and Vishnu got to take an avatar to protect the people from those Asuras. May be it's a political move against Siva worshippers.
But I don't care what there scripts say since Siva is the creator, protector and destroyer.