Think e-bikes all have more robust construction than standard bikes, so if it's ok for a standard bike, should be fine for an e-bike, whether seat post- mounted or axle level-mounted.
I use one with an ebike for towing a large dog or groceries. You'll reduce the battery range a little with a trailer but it does allow you to accelerate quickly. It's fantastic for going uphills with a load. Just keep an eye on the brake pads and chain as they will wear out a little quicker due to towing a trailer.