Potential problems:
1. The anvil isn't really holding that ground up powder in the cup. By turing the case neck down and tapping it, I'd be willing to be you could get a fair amount of the compound out of the cup.
2. By doing this, you're putting pressure on the match head compound with the anvil. If you've ever experimented with the stuff, you'll know that it can be set off without very much pressure being applied. Pushing on it with a knife blade on a hard surface is sometimes enough. You'd want to let them sit for a while before you actually reloaded the case....just to make sure.
3. I don't know how well this would work with ball an extruded powderss. I guess it could, but for easy ignition, you might want to try and stick with a flake powder.
4. You'd die of old age trying to get a box of these done.