“Puddle-wonderful” is a made up word, a syntax. Syntax means “the arrangement of words and phrases to create well-formed sentences in a language.” So the author is describing the mud as wonderful.
It reinforces the significance of a single word.
He is concerned,because he thinks Anthony will only be happy if he plays soccer
It means that even it everyone is doing something wrong, it is not right. It is referring to peer pressure, don't do something just because everyone else it doing it.
That is not non-assertive behavior. Non assertive behavior is when you are feeling dishonest or indirect emotionally.
