Maybe this process is somewhat easier for moderators but of course you don't have to be a moderator to make that little research, it's based on public information.
A moderator will likely see reports from users in their trust list, which may play a role in deciding if they can be trusted or not. There also may be non-public information in the staff section about certain users.
Conflict of interest must be avoided whenever possible, that's true for anyone with power, here and IRL.
I agree with your statement, however I disagree with your conclusion that this presents a conflict of interest.
With the exception of philipma1957, I don't think the change in trust score reasonably changes the community perception of how trusted these people are.
Except for hilariousandco, and SaltySpitoon I don't think any of the staff members engages in any meaningful trades on behalf of themselves, so their trust scores are arguably irrelevant. One could also argue that their global moderator tags contribute more to their ability to be trusted than their trust score realistically would.
Although dooglus has been involved in very shady activity, he has handled tens of millions of dollars (when bitcoin was in the low triple digits) worth of other's bitcoin, and returned said money when his website shut down. If someone is doing their research on dooglus, his trust score will probably be a very small factor.
Both tomatocage and OgNasty have handled millions of dollars of other people's money (over time), and have for a long time been arguably the most trusted members in the community, and their increased trust scores do not change that.
I would be more concerned about DT1 members adding people to their trust list, and the result is certain 3rd parties' trust scores are inflated substantially. This could be an indication that a DT1 member is using their trust list to increase the trust score of either their sockpuppet, or a potential accomplice in a later scam, and/or is giving certain users credibility that may not be warranted. This is much less transparent than what you are describing, and has the potential to cause damage multiple times.