Yes there are lots of times when I am not there. I can also as a parent let them know what a dictionary is. If I don’t know the meaning, we can look together. Nowadays it’s all screen, screen, screen. . . do I want to train them to go to the computer for all their questions? I do not!
It’s not coddling to answer a question. They should come to you with questions! Part of the answer may be to teach them how to solve something, but, “look it up” is a brusque brushoff that shows you don’t care enough to answer.
I am going to disagree with you. The beginning when you are teaching them to read is "let's look it up". You also wants to do this because, especially as they get older and the words more complex, you maybe wrong. The word excise can mean to cut something out when you are using it at a verb but it can mean a tax when used as a noun.
The next step is "what did it say when you looked it up?" If they are reading books that are from other countries the word may mean something entirely different there.
In this case by telling him to look something up she found that he really did not know how. It she had just answered she would have blithely kept sailing along not knowing that a crucial part of his education was neglected.