Regarding the tag, I will suggest a neutral tag if it is really needed [no tag needed to be honest]. The user has positive history in the forum, there are no need to give a red tag and destroy his motivation to stay positive in the community. We saw many cases in the past, and lost many good forum members too because of harsh use of feedback system.
I've always said the standard MO here is to gain trust then scam - look at the history of staff and treasurers.
Now that he has tried his scam and failed, why would he even want to stay here? Ignoring this would just empower other scammers.