Let’s say a man decides to change his last name for no other reason than he hates his dad’s last name, and that dad refuses to call his son by his new last name. Then, in my opinion, his son should be 100% allowed to call him any mean name or slur he wants—‘dick,’ ‘shithead,’ the R slur, whatever. You shouldn’t get to disrespect people and expect respect back, so if this person gets called a slut and gets mad, I really can’t feel sympathy for him.
I’m not saying it’s disrespecting the family name, I’m saying it’s disrespecting his father specifically, and that’s fine.
I think the religious opinion analogy is slightly different, this is someone who:
That is a valid thing to do, but it is directly disrespectful to the other person because it directly expresses the fact that they don’t like them.
It is fine to not respect people based on their choices and behaviour. It is fine to express disrespect to people you don’t respect.