First, to correct Quizfan's question -- it's not simply the case that the baby is deaf and is not being allowed a hearing aid. In fact, the couple have said they will allow him to have a hearing aid if he wishes. The point of contention in this issue is that the couple deliberately maximised the child's chances of being hearing impaired (he does have slight hearing ability, otherwise a hearing aid would be useless).
I understand that a deaf couple would naturally find it easier to bring up a deaf child than a hearing one. I also recognise that that they wish their child to have access to deaf culture, which is perfectly reasonable. However, I still think what they are doing is fundamentally wrong and selfish.
Had the child been hearing, they could still have taught him Sign Language, and he would have had access to two cultures, and therefore be enriched twice over. Instead, they have chosen a path of deliberate social exclusion, just to suit themselves.
To put it another way, will they exercise control over the child's sexuality? If not, what's the difference?