The person is dead. They don't care anymore about Facebook. Let them fade, remember the good times you shared, and move forward. Honoring someone's memory doesn't mean canonizing them. If that person was the only thing keeping a group of people connected, then their absence means that the group should drift apart and move on - that's how humans should work.
Once upon a time people all lived in the same village all their lives and could visit the local cemetary to lay flowers and remember. Now many of us live a long way from people we care about. My friend died on the other side of the world and for me her facebook page is the only memorial I can visit. Dead people don't care about stones or urns or trees or park benches with plaques either - all that stuff is as a comfort for the living and I don't see why a facebook memorial page should be anything different.