Guess you have to check the Terms of travel with AA, whether body odor is in any way mentioned or be limited? guess not
Then, you have to define a method of measurement to reflect what body odor is acceptable , which is tolerable and which is offending;guess there is not one as smell is a very subjective issue.
Then each plane should have that measuring device or trained nose? to confirm that the body odor falls in the unacceptable category, guess there is not.
Good luck to the mal-treated passengers.