Why did Cabral burn captured merchant ships?

Was burning the captured merchant ships a waste when Portugal might have reused them?

The hulls were useful, but Cabral lacked crews and would not leave them behind; towing them to Cochin was possible, though it might have reduced his ally's dependence.

The seized Arab hulls had value, so destroying them did waste potential prizes. Cabral lacked crews and was unwilling to leave the ships for an opponent to recover. Towing them to Cochin was a conceivable alternative. Strengthening Cochin's own fleet might also have made the new ally less dependent on Portugal, though this is a possibility rather than a documented motive.