The Citi/Vantage split was not related to any specific concerns with the airport investments but rather reflected a much broader change of strategy. The airports were a tiny part of Citi's troubled infrastructure division.
See
Citigroup Seeks to Exit Alternative Investments Unit - WSJ
The airport j-v with Peel was just a victim of this wider change of strategy, rather than the cause of it.
The only other thing I would say on 003 1/2's interesting contribution is that Liverpool did have a positive Ebitda when it was sold to the j-v, so it was reasonable to attribute a decent value to it. The same couldn't be said of DTV and Doncaster, however, which presumably dragged down the overall value of the group of airports.