The term "Troll", as with many other 'net terms' has been around since the days of barnet and fidonet, way before average people started buying "word processors with an internet".
Net abuse can be serious in extreme cases, but i'd have thought that most reactions to messages like that would have been "weirdo...moderate" followed by a plethora of "+1"'s, rather than PR companies becoming offended.
However, I don't see definitions listed for "grossly offensive", "indecent", "obscene" or "menacing". I appreciate that it's impossible to specify exactly what actions are within each of these definitions, but it seems to me that it's widely open to interpretation. Quoting one of Mark Thomas' stand-ups: "one man's shit is another man's crap is another man's poo". Someone claiming to have had sex with the dead body of a child who has been killed in a dog attack would clearly be in contravention of the above law in my opinion, but I'm sure there are some things that I would find grossly offensive that other people would not and vice versa.
I also wonder where freedom of speech fits in with this legislation. Freedom of speech doesn't mean freedom from responsibility from your actions, but it just seems like this legislation is too open to the opinions of the people who are hearing the case.
Because they were explaining things to a jury, and juries being made of the general public and all that are probrably quite stupid, so throw in a popular/infamous feature of the internet that gets a lot of press coverage and the jury might understand better. Try not to feel so patronised.