On one hand, I know someone who was banned for their sister's multiaccounting and I have interacted with both of them at once, so it really was two people. On other hand, "I have a family member and I am totally not breaking the rules" is an extremely common excuse.

On third hand, I have reported several obvious multi-rings and staff response time was in range of literal years, so I'd personally say that the worst thing is the time range between offense and response and most of these "unfair bans", this one included, would be (or feel) less unfair with faster responses.