Section 44AB has five clauses (a) to (e), of which clauses (b) and (d) are related to professional income. Also note all such clauses are separated by the word 'or' which means all are mutually exclusive. If clause (b) applies then clause (d) cannot apply. Clause (b) applies if presumptive scheme is NOT opted. In this case even if income is below 50 percent of gross professional receipts audit will not be required if turnover is less than 50 lakh. In this case ITR 3 has to be filed.
Clause (d) applies only if presumptive scheme is OPTED. In this case ITR 4 will be required to be filed.
In the given case querist is NOT opting for presumptive scheme thus clause (d) will not apply. He is covered by clause (b). Thus even if his income is below 50 percent no tax audit is required since his turnover is within the threshold limit of Rs 50 lakh.
If above replied view is taken then no professional can declare any income below 50 percent which is an absurd interpretation.
Hope this clarifies.