Talking about the tag, I would not say much about it as I am not a DT member to be in a position of taking any decision of such nature.
DT status doesn't stop you tagging someone - but inappropriate tags can be questionable. You are not required to be on DT to send any tags to someone if that is necessary - but you do need to consider something reasonable as a reference if you want to tag someone if based on other users' accusations.
Users mentioned by the OP certainly have motives and reasons for making loan requests - but we will never know exactly what their motives are. He could have wanted to get a loan because there was something urgent - but he didn't get it because his account didn't have regular activity like most other borrowers.
Would it be OK to leave a neutral tag on the profile about the loan incident after a long period of inactivity, just to act as a heads-up on anyone who might attempt to deal with the account in future?
I wanted to add one to the profile, but I don't want to be trigger-happy with tags which could easily draw criticism if they are unnecessary.
Of course - I think you can do it - IMO, but I'm tend to agree if you put it on a list of users you distrust.