show your rule

Obviously he is correct because the smallest base that can represent 10 is base 2 and 10 in base 2 is equal to 2 in base 10. And the smallest base in which you can represent the number 3 is base 4 and 3 in base 10 in equal to 3 so 2 is the smaller number hence "10" is the smaller number. And from the drawing of the rainbow you can infer that he wants to use a diverse range of bases and not just the common base 10. Btw I am only talking about the natural bases (whole number positive).