I don't think that's an issue, especially with the projected use cases. The article says that they're aiming for battery storage of about an hour of flight time

I don't think that's an issue, especially with the projected use cases. The article says that they're aiming for battery storage of about an hour of flight time, which is plenty for takeoff, final approach, and other situations where you'd want a lot of power in a hurry. Most of the flight, unless it is a very short commuter-type flight where you can conceivably charge with shore power between flights, is going to be running much like a hybrid car, with the jet engine powering a generator working at the best point on its performance/economy curve. So it'll still use fuel, and still get lighter as the trip goes on. Also, those batteries mean you don't need a set of engines that need to handle the power needed at take off, so those can be lighter as well. So I imagine that a 1:1 replacement capacity-wise would probably have at worse the same empty weight, taking into consideration the lighter engines and the smaller fuel tank that would be needed.