Neither the OP nor I said anything about a law. I can guess, however, that you are thinking about a narrow definition of the word "legitimate."
Besides references to the rule of law, Merriam-Webster defines legitimate as "being exactly as purposed : neither spurious nor false" and "conforming to recognized principles."
Intentional sandbagging is a false presentation of your abilities to prospective competitors and does not conform to the recognized principle of honesty.