Patron,
It's true that the FBI is a tougher nut to crack, but I truly believe that there are ways the BP CEO could have done things that prevented the FBI action in the first place. Your post presumes identification of a player within the FBI but that is not where they should have been looking. The guy they should have been looking to pay was Dave Pecker (appropriately named) of the National Enquirer. Had these guys befriended Cohen and Pecker it would have been very easy to set up a hush-type payment to Pecker to assist with the Trump hush monies, in other words, to essentially finance the Trump "Reelection Fund" with the National Enquirer. What I think happened is that BP got very cocky because they repeatedly won Court challenges in lawsuits brought by politicians and special interest groups. Victory was achieved on 1st Amendment grounds, to the point where they thought they were home free. These lawsuits should have been a red flag warning sign of the turbulent political waters they would have to navigate.
With foresight Carl Ferrer could have arranged a 3 way conversation with Mike Cohen and Dave Pecker and arranged a payment to replenish the "Trump Reelection Fund" that was being maintained by the National Enquirer. Then this might have all been made to go away.
That being said, the FBI is a somewhat autonomous organization operating independently of the President but after Trump fired Comey, that may have changed a bit. It was certainly worth a shot.
Although that hush fund is reported as being extensive it may have gotten its biggest boost from Stormy Daniels because her shopping the story to them enabled the payment that was made.