I wouldn't call 'regular' Piracy griefing, nor would I call 'regular' PvP griefing. But not calling any form of PvP griefing goes a bit too far for me.
Obliterating a hauler within a second in a fully outfitted anaconda already comes close, and seems useless to me. Then doing it a couple of times in a row after the hauler respawns, I'd call it griefing.
To be honest, only time I've experienced something like that was when an Anaconda blew me to bits with me having 0% chance of survival with seemingly no interst in my cargo, and all it did was push me into solo/group play for a while, the one and a half million in cargo and insurance I could handle.
Currently I don't trade in open unless I have fitted all sorts of defensive measures, mines, top rated shields and hull and some shield banks, and I'll be fine with any encounter that leaves me with at least a tiny chance on survival.