How does Nick's decision at the tea reflect that he follows his father's advice to not criticize others? Analyze it. Does Nick explain his choice? What are the consequences of his silence?

In chapter 5 of The Great Gatsby, Nick invites Daisy over to his house for tea so Gatsby can see her again after all these years. Although he also feels slightly embarrassed, Nick tries to remain polite and accepting of the whole situation.
In the previous chapter, Jordan Baker told Nick about Gatsby's romance with Daisy. Nick knows that Gatsby did not have the advantage of an old-money family and therefore was unable to marry Daisy.
So, Nick invites Daisy over and tells her not to bring Tom, but he does not tell her that Gatsby will be there as well. This way, she is not the one to make the decision to see Gatsby or not; she can't back out because of fear. Gatsby and Daisy meet in Nick's living room, and after they greet each other there is a long pause. Nick feels awkward in the hall, so he goes into the room where there is more awkward silence. Nick observes how awkward Gatsby and Daisy feel. He tries to release the tension by asking them to help him make tea, but then Finn brings some in. He chats with Daisy for a bit as they drink and then excuses himself so they can be alone. When Gatsby follows him, Nick says,

“You’re just embarrassed, that’s all,” and luckily I added: “Daisy’s embarrassed too.”

He tells Gatsby to go back into the room and then walks outside for a bit. After some time, he goes back in:

I went in—after making every possible noise in the kitchen, short of pushing over the stove—but I don’t believe they heard a sound. They were sitting at either end of the couch, looking at each other as if some question had been asked, or was in the air, and every vestige of embarrassment was gone. Daisy’s face was smeared with tears, and when I came in she jumped up and began wiping at it with her handkerchief before a mirror. But there was a change in Gatsby that was simply confounding. He literally glowed; without a word or a gesture of exultation a new well-being radiated from him and filled the little room.

Nick tells them it's stopped raining, and Gatsby invites them both over to his house.
All of Nick's actions reflect how he is very careful around the two and conscientious of their history. When he does talk, it is only an attempt to help them diffuse the tension. Embarrassment seems to be the only explanation Nick directly offers for his actions during the tea. Otherwise, he does not directly say why he invites Daisy or why he leaves to give them alone time. We can infer it is because he wants to help Gatsby, which has the consequence of setting their affair into motion and ultimately leading to the final events of the book.
Nick does not judge Gatsby and Daisy during the tea, because he too feels awkward, and he understands their history. By inviting them to tea, and walking out to give them alone time, he helps rekindle their romance.