Anakin takes a seat and lets Ezra serve himself. Although he knows how everyone in the Kenobi household takes their tea at this point, he also understands that having something to keep your hands busy when you're nervous can help.

"You're worried that he'll give up on teaching?"

He knows Obi-Wan, rather, Ben goes on to teach Luke but that is back home. Here, Luke doesn't need to be trained to keep himself alive.