I agree it makes little sense. I assume he really has a stomach virus. Hopefully this will heal quickly.
This cancellation means he will go more than six months without a match. Last one was June 29th. Next will be December 31th at the earliest. That's a long gap. He really needs Doha if he wants to be prepared for AO.
I think whatever happens come 31st December, it would be wise for Nadal fans to lower their expectations significantly
for the Australian Open. It would be close to a miracle for him to win it with so little match-time beforehand.