Is the reimbursement plan illegal or just ethically questionable?

Blake was $21$ years of age at the end of the year. During the year, he was a full$-$time college student. He also worked

part time and earned $$8,000,$ which he used to pay all $$6,000$ of his living expenses. Blake's parents, Troy and Camille,

claimed him as a dependent on their joint tax return. After filing the return, Troy and Camille told Blake they owed him

$$3,001$ for his annual living expenses. What do you think of Troy and Camille's strategy to claim Blake as a dependent?