Good little question to test the brain this morning

[jdw3018]

Got this in my weekly rules questions email.

Before the last free throw of a multiple free throw situation #42 from Team B is beckoned into the game for Team B. #32 goes to the bench and sits down. As #42 approaches the free throw lane, the official notices that his jersey is untucked and sends him out of the game. #32 gets off the bench and returns to the game. After the successful free throw, #42, who has returned to the table, is beckoned into the game by the officials. Were the officials correct?

Please respond with whether the officials were correct and, if not, what should have happened.