Thanks, this seemed obvious to me too. But I would add, this could apply to orange too - there are a lot of orange tones between yellow and red, and if you likewise wanted to determine your subjective boundary, which this is only about, you would be able to say "rather red for me" or "rather yellow for me", regardless of the intermediate color. Since the space of colors can be described as convex, so to speak, you can between every two arbitrary colors determine your subjective decision boundary, regardless of any color in between. The premise is just accepting to ignore those colors.