Rules need to be clear

[GommeInc]

Looks pretty clear to me tbh!

He's technically not accusing - he's stating fact The vBulletin was nulled, therefore it's fact.

You could write somewhere, either in that rule or another rule that members should not cause arguments, be it as accusations or as fact, causing unnecessary friction in the forum. Letting users state that something is wrong is fine, but if it opens up to arguments then a moderator should step in.