Sour grapes is an expression originating from the Aesop Fable The Fox and the Grapes. It refers to envious behaviour, especially pretending to not care for something one does not or cannot have, called cognitive dissonance.

or, Acting meanly after a disappointment

http://www.phrases.org.uk/meanings/sour-grapes.html

Perhaps, the definition, as used, should be given by the author?

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Be well