Hansol - in the case where there is only 1 credible buyer for slots, it's possible to play a waiting game. When there are 2 or more rival credible buyers for the slots, the strategy of playing a waiting game becomes more risky, particularly when the slots are in high demand and supply is relatively low.
You might wish to take a look at page 11 of this report from ACL to get an idea of general slot scarcity.
http://www.acl-uk.org/UserFiles/File...n%20Report.pdf
At Gatwick, there are at least 3 airlines that would be interested in a large number of slots and several other airlines that might be interested in a few slots. We thus have a competitive auction for one of the assets of a struggling company without taking on any of the undesired liabilities. If Easyjet (for example) were to just wait, there is a plausible chance that IAG or Ryanair would make a bid for Flybe's slots instead.