He cannot deduct overtime that was paid at his regular hourly rate. The deduction is only for the amount that is over the regular rate. If his overtime rate was $102.93 (time and a half), and he was not an exempt employee, he would be able to deduct the extra $34.31 per hour, the "half" in the time and a half rate.
The fact that he does not get time and a half for overtime shows that he is exempt because, if he were not exempt, his employer would be required by law to pay time and a half for overtime.
