One of his terrible justifications was that it was a reaction against all the "hypocritical" posts from people who didn't know the victims saying how much they would be missed.
Whilst it's not a great justification- and certainly doesn't excuse the extreme actions of trolls, I do agree with this.
A friend of mine has a blog and every time a celebrity dies, he'll have a post about how wonderful they were and how much they'll be missed. It's grief tourism.
My kneejerk reaction is always to say "Well I'm glad they're dead, and here's why...".
It's a reaction to the bandwagon jumping, not the actual event.
If he really had strong feelings on how the grief tourists were reacting he could have responded to their comments by saying "I think you are being a hypocrite" or even "stop getting off on human misery, you weirdo".
What he seemed to do was scour Facebook for memorial pages (and why shouldn't families do this? It just seems like the 21st century version of putting a notice in the paper or sending out black edged cards) and then spam them leaving all kinds of vitrolic abuse while hiding behind a false user name, or indeed creating accounts using the real names of the person who had died, editing photos of them and posting sick videos about them.
Both sick and spineless.