Yes they can.
Plenty of manufacturers make crankshafts that are not nitrided. They're turned all the time. Simply because the material is soft(er) doesn't mean it will not work. Take a look at bearing material. The material on the top layer is much, MUCH softer than the material hiding underneath the nitrided layer. The key is to get the right finish on the crankshaft.
HOWEVER... They shouldn't unless the plugs are removed from the cross drilled passageways. There, abrasive particles will hide until you go to the track the next city over, with a new setup, and are hoping to hit 11's. Then, they'll come out to play, and you'll be mad and break up with your girlfriend...
Holy crap. JD made me ponder for a second... With the softer material underneath, and the significant timing advance in most of these motors, will the force of the rod hammering on the crank wear it *unusually* faster if it WERE reground? I'm thinking of the rod journals, here... Mains would certainly be fine.
No, I've reconsidered my opinion. It's fine with the precautions above.
The human torch was denied a bank loan.