Well, since the balance nerve and the hearing nerve are a "two for one" deal - they're both wrapped in the same insulation - I'd find it hard to believe that anyone could say they are not related.
I had absolutely no hearing loss in my AN ear, but when I had my vestibular testing done, it was determined that my balance nerve was only functioning at a little over 40% of it's capacity. Because the damage to that nerve was gradual, my other side was able to slowly compensate and take over the extra work for the AN side. It really depends on the position of your AN - mine happened to be more on the balance portion of the nerve, but a lot of other people had hearing loss and no balance issues and some had both. Location, location, location.
The virus theory is a little hard to understand as well, because if the virus attacked your balance nerve, why didn't it affect your hearing nerve as well? Maybe someone else out there has an explanation for it, but it sounds a little fishy to me. I think I'd ask a few more questions of the people who gave you this information.
Lori