I have had a similar experience with a friend who died very young (probably suicide although I've never had confirmation). Anyway now every year a bunch of people still post something for his birthday some comments are followed by RIP others are not. I suspect some of these people still don't actually know he's dead and post a message directly through their newsfeed without looking at his profile. It's pretty awkward but it's not my place to go and tell them (I don't know most of them) "FYI, he's dead"