No, it is completely inappropriate. Watching someone undress without their consent is a serious invasion of privacy, especially when it's a family member. Such a topic involves unethical and improper behavior.
Yes, it can be normal in many cases. For example, when the daughter is a young child, it's quite common as moms often help their young daughters with bathing or getting dressed. There's a natural level of comfort and lack of self - consciousness at that age.
She should assert her boundaries clearly. No one has the right to force someone to do such a private and inappropriate act in public. She might also consider getting legal advice as this could potentially be a form of abuse or harassment.
Telling such a story goes against basic moral and ethical values. Everyone has the right to privacy, and a wife's privacy in this regard should be protected at all costs. It also shows a lack of respect for the relationship between husband and wife.
One alternative could be for the son to call a female family member or friend to come and help. For example, an aunt or a neighbor who is female could assist in a more appropriate way.
No, it is not ethical at all. Watching someone undress without their consent, especially a family member like a cousin, is a serious invasion of privacy. It violates basic moral and ethical boundaries and can cause a great deal of harm and discomfort to the person being watched.