Itachi had to strike a careful balance between his work and his clan household. Too much time at work, and responsibilities and expectations were thrust on Sasuke. Too much time in the compound and he would be hassled about when he was going to find a woman and settle down.

He surmised he only had a few short years before Fugaku thought about stepping down, or really training him on how to take over the Uchiha clan. That is, provided he isn't pulled from active duty for his heart condition.

"For now, I am free." For a few hours, before he tried to get some sleep before the next shift. He offers a faint smile Sasuke's way.

Let them enjoy the rare free time they both share.