Wow - that sounds like a mediocre experience indeed.
And I fully agree - it's a business decision to have Obama stay at the Adlon, along with all the security restrictions and the major inconvenience to other guests. Blaming "force majeure" is laughable.
If I had spent multiple hours standing in the cold/rain (on more than one occasion, as it sounds), I probably would have had a "nice" discussion with the GM why I wasn't going to pay for that stay. A 7% discount is more of an insult than appropiate compensation.