Rhino - presumably because Lufthansa did not come up with enough readies for him to be satisfied the scheme had enough cash to discharge it's future liabilities despite the trustees being satisfied with the deal after receiving independent financial advice.
The amount Lufthansa has "volunteered" (£84M) to give now, to part way supplement the PPF scheme, is the same amount they had pledged to keep the scheme running as was. Guess they won't stump up any more.