A couple of points...
1. No-one outside of Abertis and bmibaby will have any real idea as to the charges imposed on the latter by the former;
2. Groundhog is quite correct - the comes a point where if the charges required by the airline are lower than the airport's costs, the answer is 'thanks but no thanks';
3. Why are bmibaby's motives being questioned? Perhaps they had really good reasons for leaving....
A lot of uninformed speculation going on. Not good and not helpful...
TA