Not sure if I agree with this one.
Is it terrible when you give an item to a friend and never have it returned to you? Yes.
Is it anyone else's fault but your own? No.
Although I understand the point you're trying to make, I disagree that saying "read the rules" as a staff member to a player who lost items from a trust trade is supporting scamming. Does it come off a bit rude? Sure, I'd agree with that, but staff members are here to enforce rules and be impartial, not choose the side that best suits someone else's interests.
Players are given the freedom to lend their items to whomever they wish to, and if they make that decision, knowing full well that it is their choice and their choice alone, then they should be responsible for any ramifications that come along with it. That just makes sense to me - the difference here is that the choice is being entirely made by the person lending the item out. They are not being coerced to do it, nor is it being done against their will. The ideology is similar to how refunds are handled. If you lose items from a server-related bug or DC, then you'll be refunded. If you lose items from a bug that cannot be verified or a DC on your end only, then you won't be refunded. The difference is that the onus falls a lot closer to the player than anyone else in the latter, which is why it is similar to how trust trade "scams" handled.
You can look at it from the perspective that turning a blind eye only allows it to thrive, or you can see the non-intervention as a measure to actually prevent people from loaning their items out. At the very least, if people know staff will not get involved, it prevents them from thinking there is a guarantee of getting their item(s) back. That is why that specific paragraph is in place instead of it just not being mentioned in the rules.
In any event, afaik, the main reason that staff do not get involved is because a lot of the reports get so complicated and difficult to follow that it's hard to find a solution that is just. It's usually people pointing fingers at each other and submitting evidence that is unclear. Now, this is where I'm going to steer the boat in a different direction. My actual opinion on this is that I'm neutral. No one can deny that it's wrong for a player to keep an item that they were entrusted with; that's just a fact - plain and simple. The staff team isn't and shouldn't be responsible, but I wouldn't be opposed to them taking on the responsibility of reviewing trust trade "scam" reports. Although I can anticipate a lot of the reports going nowhere, there will of course be reports with legitimate evidence.