As BJ said, a judgement call.
Boxes are designed for raceway/cable/etc entries and containing conductors. Modifying the box, by drilling a hole, could be considered a 'violation of the listing' or 'not complying with mfg directions/instructions'. No intention of starting a "definition and wordsmith debate is intended!
It is probably cheaper (labor) to install a beam clamp, then to invest time in drilling the box.
Your AHJ may require the beam clamp/hook, and closing the hole you drilled, so you may end up replacing the box if you can't satisfactorly close-up the hole.