Wasn't the son used to blackmail Flynn into admitting to lying to the Feds when he had not done anything of the sort? Do this or we go after your son? And considering there is now no need for a person to actually do anything illegal in order to get in trouble with the legal system - or actually there are so many laws that nobody knows even half of them, not even the damn lawyers and judges, and it is always possible to find and twist something so that the most saintly and law-abiding person ever could be accused of something or other and get tied to courts for years - that was good enough a threat for him to yield.

And they got him out of the way for four years.