In revoking the visa a second time, the government should have cited the inaccurate statements on his visa application, rather than "health and good order grounds." Djokovic claims his staff made the mistake, but that doesn't matter in most countries—the applicant is responsible for the accuracy of the information submitted regardless of who prepared it. (Similar to how courts won't tolerate an attorney saying his secretary messed something up). Saying "you lied on your application" (which, by all accounts, he did) is more powerful than amorphous "health and good order grounds."