Even if the scandal required the entire sanyaku to be redone, no asterisk is needed nor deserved. This isn't Hakuho (or anyone else for that matter) taking PEDs or the like to gain unfair advantages or victories. Hakuho is fighting everyone eligible to fight. If other rikishi have to go and get themselves banned by gambling or associating themselves with the Yakuza, no skin off his back.
Now, if it comes out that yaocho was involved in some of these cases, then basho/rikishi get asterisks. But that hasn't been proven...yet.