I would work on a **fire starting technique** which doesn't rely on airflow from wholes in the bottom.

* Basically use any technique that you would use in an old-fashioned chimney or a campfire on flat ground - in both cases you have to make due without venting from directly below.

While creating wholes would certainly help, it would also create problems:

* Ashes, embers, coals, etc. would fall through while using it. To avoid damaging whatever you use the fire bowl on you'd have to add some heat-resistant container to catch them.
* As @JamesJenkins mentioned, drilled wholes will speed expose the non-coated core of the bowl, and thus allow for rust.
* Last but not least: you'd have to make quite a bunch of wholes to get a lot of airflow, at least if you're not paying a lot of attention to fire starting/building technique. And if you *are*, I'd say there shouldn't be any air flow problems even without wholes. :)