Personally, I see no reason to trust such a user and adding him to the DefaultTrust looks very strange. Am I right to understand that you can trust user feedback without proof?
It's good that it looks strange, and it's fine if you don't trust them. That is one of the best examples that this new DT-1 selection process is working. It's meant to capture varying opinions and perspectives on trust related issues. Everyone has different reasons for their inclusions and why they feel someones feedback, flag support, or general approach to forum dealings. It helps provide a much more rounded trust system, a far cry from the old method.
Not sure what you mean by trust a user feedback without proof. I don't use Default trust, I've made my own custom trust list, which is something all members should do at some point once they get the handle of the system. From what I can tell they have left feedback, each with a reference if that's what you mean by proof. Enough people out there obviously trust them and their judgement so who am I to say that they aren't worthy to show feedback to Newbies by default.
Now if you have any reason besides them being a bounty hunter that they shouldn't be trusted. You can start a reputation thread,or PM people who have included them and make a case. The DT system allows for dt-1 inclusions to remove users after they've been voted in.