She was not convicted of any crime sufficient to bar her from entering America, but the Americans use the " Moral Turpitude" law when it suits them, and elements within it, in short this means among many other things, "Conduct that is considered contrary to community standards". They have these???
Most likely, almost 100%, if it hadn't been found out, spoken / shown about in the media that she took drugs in front of her kids she would have been allowed into America.
Because of her high profile in the USA they took a bit more interest in her trial.
Her ex-husband might find he will also, if they stick to the system in place, be banned as well.
But then double standards go hand in hand with the Americans when it suits.