I think theymos purposely doesn't give official guidelines because he wants it to be a more community oriented decision. I don't believe everyone working off the same list of rules is the goal.
Everyone do not have to work from the sane list but at least there should be a guide for leaving trust feedbacks by the community. When I picked interest I thought leaving a negative feedback for ban evasion was correct but after I asked suchmoon he corrected me, asking me not to tag users for such but instead report them to moderator. I was mislead my other users feedbacks and I'm sure others are too.
On the board where this infograhic was posted there's currently an argument on leaving negative feedback for accepting or giving BTT account as collateral. This type of issue who had been avoided if we have guidelines users can turn to.