No, I wouldn't, that's like asking a scammer to admit he was scam, a scammer will do anything to deny the fact. I would be better to ask other users who active in busting scam to know their opinion, but some people I think doesn't want to get such PM, that's why I opened this thread to know other user reaction rather than I cherry pick some users.
Of course it goes without saying that if a member is a scammer, or is posting links to suspicious website, or malwares that can get other members scammed and hacked, you shouldn't send them any pm, but report and make a topic about it. Iranus' case is none of that, it is entirely up to you, but if you do not really care that a user gets kicked out of their campaign and gets tagged for something, you can send them a pm to notify them of anything you notice in their post history, or to tell them that their posting pattern of quoting posts and returning back to it to fill it up is wrong like the previous case, and they should desist from doing such, especially if that member has been in the forum for long and has ranked up. If the member is headstrong to change & still flouts that advice, you can now make a report against them.
Can you find his address on 2016-2017? if you can find it and he can sign a message, then this case will closed.
Iranus does not even have to sign any message for the case to be closed, they already told their own side of the story, i think every member can decide to sign a message to prove anything or not.
Should we not create a report if the proof isn't completely 100% convinced?
Yes.