Two millennia later, no one knows for sure who he really was. Of course things work differently today. Coerced forgetfulness is out of the question in a free society. Newspapers and journalists would have to participate voluntarily. Instead of suppressing actual facts, which are needed for accountability, good results might be achieved simply by making adjustments in style and presentation.
Courts already do have some authority to order name-changes.
The asterisk is there to let anyone find the assassin's former name in a footnote, if they are truly interested, so no one is actually suppressing knowledge. Nevertheless, the emphasis on a new moniker will take hold. Judges could get creative, or the public might be invited to suggest appropriate derogations. It would reflect society's determination to allocate fame properly, to those who earn it. By harming innocents, you're only destroying your own name.