Well, it might be a project by ChrisFix. Maybe his mom has an interesting life experience or a story to tell, and he is making efforts to get that story out there. It could involve things like interviewing her, collecting relevant photos or mementos, and then presenting it in a format that can be shared with others.
It's not ethical at all. Think about it. You have a certain relationship with your friend and his family. This act would shatter the respect and normalcy in those relationships. It can lead to a whole host of problems like emotional turmoil for everyone involved, and it's just not something that society deems acceptable.
This is a very inappropriate and abnormal situation. One possible consequence could be severe emotional trauma for the son. He may grow up with a distorted view of healthy relationships and boundaries.
Bring in some objective proof. If it was an event related to school, you could show her a note from your teacher or a text from a classmate. If it's a personal experience, like seeing a strange animal, you can find information about that animal online to support your claim. This way, she has something more than just your word to go on.
One consequence could be that she might not be able to attend to her children's needs if they suddenly require her assistance. For example, if a child has a nightmare or gets sick during the night, a drunk mom on the bed may not be fully aware or able to respond quickly.
In many stories, disrespect is also a cause. Saying rude things to mom or not listening when she's talking. Moms spank to teach kids to respect others, especially family members. It's their way of instilling good values in a rather tough but sometimes necessary way.