This is a really exaggerated view, and complete guesswork, but if the bids were, for example:
Lamb - I will get us through the year, pay off creditors as much as I can, and rebuild in the championship
Koukash - I give you 3 million pounds and it will all go on great players, and when the Bulls are great again, I will pay people off.
Under those options, the administrator has to give it to Lamb.
I know it's nonsense, but Mrs Koukash does say in her tweet that the decision was about paying creditors.