They do allow users to indicate their preferences. "Memorialization is our default action, but we know that some people might not want their account preserved

They do allow users to indicate their preferences. "Memorialization is our default action, but we know that some people might not want their account preserved this way. They might prefer that we delete their profile. Recognizing this, we give people a way to let us know they want their account permanently deleted when they die. We may also delete profiles when the next of kin tells us that the deceased loved one would have preferred that we delete the account rather than memorialize it. Other people might want a friend or family member to be able to manage their profile as a memorial site after their death. That’s why in 2015, we created the option for people to choose a legacy contact. A legacy contact is a family member or friend who can manage certain features on your account if you pass away, such as changing your profile picture, accepting friend requests or adding a pinned post to the top of your profile. They can also elect to delete your account."