I think maybe he either figured he had plenty of time to take the queen as long as he could keep checking me or maybe he thought he could checkmate me quickly without taking it or maybe he thought my rook on the open file after I recaptured was a bigger threat. He had so much power in the corner with my king that there was no way I should have been able to get out of it.
Black resigns because it's a slow death march down to the corner, he should have won, though.