I would say no, don't buy it. Get the correct size which will be a size large. Its a lot of cash. You might as well buy the correct size. The wrong size bike will be there long after the enjoyment of cheaper price has been forgotten.
With E bikes if in doubt downsize. They are heavy and stable and you dont need to make them more stable by buying one thats longer than optimal.
At 180cm I role with a size medium because i like a more maneuverable bike. I too should be on a large according to the recommendation but i say no!. Give me the faster handling bike. Noting that I come from and still do mountain bike with lighter faster handling bikes.
With that said, as you are a moto guy and have zero mtb experience you wont know the difference if it is too big or not. It will feel light and maneuverable by comparison to a moto.