While it's hard to agree on a absolute definition of griefer, I'm personally ok with wikipedia's "A griefer is a player who plays a computer game in order to irritate and harass other players, rather than in pursuit of game objectives." then, as players are mainly encouraged to have their own objectives, a player who has the objective of 'moving people's runestones around' can't be considered a griefer. The term is being overused quite a bit, I think.
Being able to read things from a distance sounds good to me. It would also be nice to be able to erase a runestone a limited number of times, whether it's for fixing mistakes or reusing for different purposes or (friendly/creative) vandalism.