[...] one of legendary staff members started promoting obvious ponzi with avatar/personal text [...]
You cannot expect staff to judge whether or not a specific service with a referral scheme is legit or not.
So there's only two possible solutions to the dilemma of staff sometimes accidentally (or willingly) promoting scam:
1. forbid advertising for staff
2. let them do whatever they like
I personally would opt for 1.
I think it is pretty clear that in this case the site that is being advertised is a scam. That is the major difference, sure someone could get duped into advertising what turns out to be a scam, however the evidence is clear.
Possibly. But I still don't think the burden of judgement should be on the shoulders of staff.
There may be other cases (and have been in the past) where the situation is not as obvious, and where the advertising by staff might have lured a lot of newbies into believing some scam to be true.
That's why I'd personally discourage staff and legendary members from promoting any business (except for their own, if they have).
Making that a rule for staff or e.g. users on DefaultTrust would be a good idea.
I think that anyone who advertised such a obvious scam is someone whose word should not be trusted, and is not reputable and the forum staff, and more importantly, the people on level 1 default trust who be trusted and should be reputable.
I agree, but I'd prefer a solution for the future over making an example of this singular event.