It’s not true. I have been implanted after 20 years of completely ZERO hearing in my left ear with positive outcomes. If it weren’t for reimbursement issues(?), you’re in an even better situation because you have a relatively good tonal audiogram and continuous stimulation with a hearing aid. Maybe you need second opinion? Many ENTs and Audis still stick with old obsolete guidelines. Well, unless you live in the UK, then it’s harder.