Ummm... sounds like fun. But, I believe in the uniform. Not so much for tradition. But I understand the need for a display professionalism. Respectful dress and professionalism helps keep training in perspective. It's okie to joke around every now and then, but we are here to accomplish something.
Plus, professionalism is preferred for potential students. Maybe he has nothing investing in the success of his dojo? Frankly what school would you join: the people dressed respectfully who are training with a friendly and professional attitude; or the school with ninjas and power rangers?
If you prefer the power ranger clothing, then we now know of a dojo that would facilitate those needs.