The shovel pocket on this bag is designed for Voile Avalanche shovels, which are the most commonly used.
You are right that (ironically) the Burton shovel doesn't fit this pack. But they don't sell many of them. There are some interesting retrofits discussed on the (old) BMB, such as sticking an old ski pole handle into the shovel blade, so it fits the packs shovel strap and holds it in.
Its worth just getting a Voile shovel if you have this pack, though.
You can even get them with probes, snow saws, or wood saws stashed in the handles. Pretty Sweet.
Check them out:
The pack designers couldn't convince the hard goods guys to change the shovel, so decided the make the best pack they could for the most common (and popular) shovel out there.