needed to be an underlying crime. And no one has specified what that was.
They were given four options, I believe, including false book keeping. It's not unusual, even in the UK, where, for example, a jury may be told that they can find for manslaughter, or murder.
The false book keeping certainly seems obvious, as he wrote the hush money in the business accounts as legal expenses. They were written off against tax liabilities.
The implacable IRS may now take an interest.