Jim,
There is Celebrity policy and then there is what happens day to day when dealing with Celebrity.
The 200% deposit requirement is on every invoice. They added this probably about 5 years ago.
Of course this is easy to get around by booking on the website, paying the requested deposit (because the Celebrity site has not been coded to double it) and then transfer to the TA.
The book onboard reduced deposit offer is for Inside cabins through Sky Suite. I can't find the documentation for this at the moment but that's what it said on at least my last 2 sailings. Not sure if they would actually charge 1 or 2x the standard deposit.
So my sort of tongue in cheek comment was with a normal $900 deposit, doubled for a deluxe suite (CS and above) for a B2B would be $3600. They paid $400 in deposits total so technically they should have had to increase the deposit by $3200.