I would also oppose a flag on Hhampuz based on the evidence I have seen so far. He has a right to make poorly formed accusations. You don't have a right to punish him for it.
The yellow box is specifically designed to warn newbies and guests. Based on the comment below I feel more justified to use it than e.g. old-school negative trust, which had a red warning visible to everyone. I believe newbies and guests should be made aware of Quickseller's bad business habits and that is not a punishment but rather information to help them make informed choices.
There are three very separate scopes for trust which need to be kept separate. Newbie-warning flags are only for warning newbies, not for warning experienced members who should know better, or for harming the target. The "#" symbol is supposed to be inconspicuous, since it's not supposed to be a warning or a "mark of shame".
(I won't rule out adding a per-post warning for newbies if people evade the per-topic warnings, though.)
You aren't presenting any evidence he is likely to lose anyone money. Your beliefs are irrelevant. Objective facts are relevant. That is the entire purpose of this new flag system, you have to provide something more than your beliefs.
"suchmoon alleges: Due largely to the factors mentioned in this topic, I believe that anyone dealing with Quickseller is at a high risk of losing money, and guests would be well-advised to avoid doing so. This determination is based on concrete red flags which any knowledgeable & reasonable forum user should agree with, and it is not based on the user's opinions."