By definition, it is not just time to my understanding.
More the intent.
If you are trying to keep an individual from returning to the game
that would be griefing.
If you have a few ships and are not worth hitting and you attack over and over at cost to you and no profit
that would be griefing
If you are hitting because you dont like someone personally
that would be griefing.
But I believe it is written so that ultimately it is the admins decision and not a group of griefers

damages or butthurt received in the posting of these words is solely yours and yours alone
if counseling is needed therapist ahben buthert or cryin ferdays is available at the tp kleenex & creme clinic

I am a silly head and a meanie.