Apparently, because the Jackass claimed to have paid the money himself, and did not take it from the Campaign he committed not 1 crime but two. This is based on the money being spent to save the campaign so, it was a campaign crime and also a crime of bribery. I heard several law dogs explaining that.
Here is a step-by-step primer on how to make the worst series of decisions possible - it relates to covering up hush money payments to porn stars:
Step 1: Deny that it happened.
Step 2: Sue the porn star for revealing it, based on a nondisclosure agreement that you weren't a part of. Be sure to use the NDA that you aren't in as evidence of innocence.
Step 3: Say that you didn't know anything about it and your lawyer did it as a favor (both the NDA and the payment), because you were such good friends.
Step 4: When that doesn't fly, say that even if you had done it, but you didn't, there wouldn't be anything wrong with it.
Step 5: Hire Rudy Giuliani to be your spokesman.
Step 6: When your lawyer flips on you because you pretended that you barely knew him and he's incompetent, say he has no credibility because he's obviously a big fat liar.
Step 7: Continue to let Rudy Giuliani be your spokesman.
Step 8: Continue to deny knowing anything about it, but declare that you paid for it, not your campaign, even though having your campaign pay for it would have been strictly legal though not ethical, while paying for it personally and not reporting it is not legal.
Step 9: Continue to claim that you paid for it personally even after your Trump Organization CFO flips on you and confirms that not only did the business pay for it (exceeding donation limits), and you didn't report it (violating contribution disclosure laws), and you claimed it as a business expense (tax fraud), and you personally directed it (a crapload of lying), and it was for the purpose of influencing an election (must be a law about that).
Step 10: Continue to let Rudy Giuliani represent you.