Nothing in the story indicates a "blocked" aisle, only that the dog was momentarily in the aisle. A momentary presence is NOT a blockage, particularly on a tarmac, particularly when they've been sitting on the tarmac in zero danger for over an hour. To say anything else is to imply that any passenger or crew in the aisle is also a blockage, and therefore stewards MUST be prevented from being in the aisles. Or are you okay with risking safety so the drink cart can go down the aisle on a short flight?
The aisle does not have to clear in flight. On the ground during taxi (try standing up sometime and see what happens to your trip plans), during takeoff, and landing. The simple matter of putting a disabled person in an exit row can result in huge fines to an airline. For the same reason.