You take the risk with /trust That's why you should "trust" the person that you set the command for, just like it has always been with regular Co/Op's. Griefing does exist, it's just not bannable because you run your own risk.
so basically, /trust someone and they can loot all your rares and its ok. thats what comes to mind... this server dosent allow or encourage such acts. everything has its limits, i doubt either /trust griefing is legal, and coop griefing to an extent (ex below). why? personally, i make agreements before anyone can be my coop. you have no permission to alter certain areas/builds of mine. if you loot me or use/take my items without permission (all my chests are locked to me, so that means through illegal means, and i dont let anyone take use or borrow my rares and etc) and a few other things, id report. if you think about /trust, its like tpaing people pre world protection. you trusted them, to not do anything wrong, so you tpd them they can edit your island they arent yer coop. /trust is post world protection, now they can edit your island (maybe even /visit while /lock is on, we will find out about that when it all works correctly), and they are not your coop. ANYWAYS, who knows wait till a mod sees the post and clarifies what the rules are on this, since this is a newer command/issue