Being banned for Ninja-Looting in dungeons[ANSWERED]

So a guild-mate of mine recently just got banned for Ninja-looting in a dungeon, how the story goes:

A rogue in the dungeon was doing generally low dps, early on in the dungeon he was attempted to be kicked as his dps was low, the kick failed as the group decision was not unanimous, the reason for him being low dps turned out that he was afk the whole dungeon and was just auto-attacking, needing on everything taking other peoples loot. The last boss comes and a dps trinket drops, everyone (exept the healer) in the group *a DK, a Hunter, A warlock, and the rogue all rolled on the item as he was afk the whole dungeon and didn't deserve any loot.

The DK rolled 80
The Warlock rolled 80
The hunter rolled below
The rogue rolled the least.

The warlock won, and gave it to the second roller who in this instance was the DK. The rogue replied "Haha Screenshotted" to which my guild-mate got a 5 day ban.

If a person needs on an item by mistake and someone submits a screenshot does this mean anyone is at risk of a 5 day ban without it properly being looked into?
If the person who reports the issue isn't the intended target for the loot is this still against the rules?

I'm worried now that these issues don't get looked into properly and anyone is at risk of being banned if you can doctor a screenshot as the logs would show that the trinket was not on his account.

He has already posted an appeal i'm not chasing that up I just want some clarity.

I would strongly suggest that you make a ticket in-game for this inquiry, or send a private message to Aldtharios (the Head GM) here on the forum.