Why did Mr. Cattanzara warn George not to do what he himself had done?

In the story, Mr. Cattanzara does warn George not to do what he himself had done. If we read between the lines, we can arrive at some important conclusions about Mr. Cattanzara's behavior here. It is likely that Mr. Cattanzara sees himself in the younger man and doesn't want George to miss an opportunity to make a better life for himself.
So, Mr. Cattanzara warns George not to do what he himself had done because he cares about him. The older man's solicitude for George is clearly demonstrated in the story. It is Mr. Cattanzara who spreads the news about George reading a hundred books. Because of Mr. Cattanzara, the people in George's neighborhood begin to treat him with more respect. The shoemaker tells George that he is a good boy, and other people begin acknowledging him with smiles. Even his sister, Sophie, increases his allowance to a dollar a week.
It is clear that Mr. Cattanzara has sensed George's unhappiness with life and wants to do what he can for the young man. So, he spreads the story about George reading a hundred books as a means of providing the young man an impetus to act on his goals. On the night Mr. Cattanzara corners George about his reading, the older man is drunk. He challenges George to tell him the truth about his reading habits. George, who hasn't really been reading, is embarrassed.
Yet, Mr. Cattanzara's intention isn't to embarrass George; it is to warn the young man not to do what he did. The implication is that Mr. Cattanzara failed to realize his life's goals, and he doesn't want George to make the same mistake. So, Mr. Cattanzara warns George not to do what he himself had done because he cares about him.