It's the first part, It was getting long.
Tho, it is ment to illustrate several things, that cats are as loyal as dogs in their own ways even though they can be choosy about the human. That some people do not deserve that loyalty. And their intelligence.
It's more understandable if you have read -Spot and Smudge-, the first book atlest.
The entire story was in part a distraction for the theft of kibble.