He's adorable and I think those other "concerned" moms acted like witches.
But I think if he had been my son, when he started worrying about what other people would think if he dressed up as Daphne for Halloween and feared they would laugh at him and he wanted to change his mind, I would have let him change his mind. I could have made him a second costume and still let him keep the first one for dress-up at home. I feel like the mom kind of pushed him to wear the costume even after he had second thoughts about it.
My daughter started out wanting to be "Cranky the Dragon" (which is a character from her imagination) for Halloween and I bought the pattern, cloth, purple tights, plastic coated wire hangers, and four cones of purple serger thread to make her a purple dragon costume with a red belly and several sets of wings. Then she had second thoughts because she reasoned that nobody would know who she was supposed to be and she wanted to be Wonder Woman instead, so I made her a Wonder Woman costume. At her request, I even made myself a "Wonder Woman's mother" costume. I still have the other stuff to make a "Cranky the Dragon" costume if she wants one later.