If you're concerned about a "lack of evidence" have one or two of the other members also file a report. Rather you were in a dungeon, gathering, crafting or RPing they were affecting your game play plain and simple. It's not a waste of GM resources.
From what I know quicksand seems to be famously ( or infamously?) well known. So sadly you gotta kinda deal with the BS as it comes. Were it me I would prefer to find taverns and the like to RP at in the housing districts. Do you guys have events or venues. For example in wildstar and EQ2 folks build and ran their own taverns. Open nightly.
For your next course of action, If you did not file a report Then if it were me I wouldn't. But for sure do it the next time that happens.